Problem:
Score : 600 points

Problem Statement

There is a grid of squares with H+1 horizontal rows and W vertical columns.

You will start at one of the squares in the top row and repeat moving one square right or down. However, for each integer i from 1 through H, you cannot move down from the A_i-th, (A_i + 1)-th, \ldots, B_i-th squares from the left in the i-th row from the top.

For each integer k from 1 through H, find the minimum number of moves needed to reach one of the squares in the (k+1)-th row from the top. (The starting square can be chosen individually for each case.) If, starting from any square in the top row, none of the squares in the (k+1)-th row can be reached, print -1 instead.

Constraints

1 \leq H,W \leq 2\times 10^5

1 \leq A_i \leq B_i \leq W

Input

Input is given from Standard Input in the following format:

H W
A_1 B_1
A_2 B_2
:
A_H B_H

Output

Print H lines. The i-th line should contain the answer for the case k=i.

Sample Input 1

4 4
2 4
1 1
2 3
2 4

Sample Output 1

1
3
6
-1

Let (i,j) denote the square at the i-th row from the top and j-th column from the left.

For k=1, we need one move such as (1,1) → (2,1).

For k=2, we need three moves such as (1,1) → (2,1) → (2,2) → (3,2).

For k=3, we need six moves such as (1,1) → (2,1) → (2,2) → (3,2) → (3,3) → (3,4) → (4,4).

For k=4, it is impossible to reach any square in the fifth row from the top.

Solution in C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using static System.Math;
using System.Text;
using System.Threading;
using System.Globalization;
using System.Runtime.CompilerServices;
using Library;

namespace Program
{
    public static class ProblemA
    {
        static bool SAIKI = false;
        static public int numberOfRandomCases = 0;
        static public void MakeTestCase(List<string> _input, List<string> _output, ref Func<string[], bool> _outputChecker)
        {
        }
        static public void Solve()
        {
            var H = NN;
            var W = NN;
            var ABList = Repeat(0, H).Select(_ => new { A = NN - 1, B = NN }).ToArray();
            var seg = new LIB_LazySegTree<(long, long), (long, long)>(W, (long.MaxValue, long.MinValue), (long.MaxValue, long.MinValue),
                (x, y) => (Min(x.Item1, y.Item1), Max(x.Item2, y.Item2)),
                (x, y) => y,
                (x, y) => y
            );
            var cnt = 0L;
            var left = 0L;
            for (var i = 0; i < W; i++) seg[i] = (0, i);
            foreach (var item in ABList)
            {
                ++cnt;
                if (item.B < W)
                {
                    var kabeQuery = seg.Query(item.A, item.B + 1);
                    seg[item.B] = (item.B - kabeQuery.Item2, kabeQuery.Item2);
                }
                if (item.A > left) seg.Update(item.A, item.B, (long.MaxValue, seg[item.A - 1].Item2));
                else left = Max(left, item.B);
                var ans = seg.Query(left, W).Item1;
                if (ans == long.MaxValue) Console.WriteLine(-1);
                else Console.WriteLine(ans + cnt);
            }
        }
        class Printer : StreamWriter
        {
            public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
            public Printer(Stream stream) : base(stream, new UTF8Encoding(false, true)) { base.AutoFlush = false; }
            public Printer(Stream stream, Encoding encoding) : base(stream, encoding) { base.AutoFlush = false; }
        }
        static LIB_FastIO fastio = new LIB_FastIODebug();
        static public void Main(string[] args) { GC.TryStartNoGCRegion(134217728); if (args.Length == 0) { fastio = new LIB_FastIO(); Console.SetOut(new Printer(Console.OpenStandardOutput())); } if (SAIKI) { var t = new Thread(Solve, 134217728); t.Start(); t.Join(); } else Solve(); Console.Out.Flush(); GC.EndNoGCRegion(); }
        static long NN => fastio.Long();
        static double ND => fastio.Double();
        static string NS => fastio.Scan();
        static long[] NNList(long N) => Repeat(0, N).Select(_ => NN).ToArray();
        static double[] NDList(long N) => Repeat(0, N).Select(_ => ND).ToArray();
        static string[] NSList(long N) => Repeat(0, N).Select(_ => NS).ToArray();
        static long Count<T>(this IEnumerable<T> x, Func<T, bool> pred) => Enumerable.Count(x, pred);
        static IEnumerable<T> Repeat<T>(T v, long n) => Enumerable.Repeat<T>(v, (int)n);
        static IEnumerable<int> Range(long s, long c) => Enumerable.Range((int)s, (int)c);
        static IOrderedEnumerable<T> OrderByRand<T>(this IEnumerable<T> x) => Enumerable.OrderBy(x, _ => xorshift);
        static IOrderedEnumerable<T> OrderBy<T>(this IEnumerable<T> x) => Enumerable.OrderBy(x.OrderByRand(), e => e);
        static IOrderedEnumerable<T1> OrderBy<T1, T2>(this IEnumerable<T1> x, Func<T1, T2> selector) => Enumerable.OrderBy(x.OrderByRand(), selector);
        static IOrderedEnumerable<T> OrderByDescending<T>(this IEnumerable<T> x) => Enumerable.OrderByDescending(x.OrderByRand(), e => e);
        static IOrderedEnumerable<T1> OrderByDescending<T1, T2>(this IEnumerable<T1> x, Func<T1, T2> selector) => Enumerable.OrderByDescending(x.OrderByRand(), selector);
        static IOrderedEnumerable<string> OrderBy(this IEnumerable<string> x) => x.OrderByRand().OrderBy(e => e, StringComparer.OrdinalIgnoreCase);
        static IOrderedEnumerable<T> OrderBy<T>(this IEnumerable<T> x, Func<T, string> selector) => x.OrderByRand().OrderBy(selector, StringComparer.OrdinalIgnoreCase);
        static IOrderedEnumerable<string> OrderByDescending(this IEnumerable<string> x) => x.OrderByRand().OrderByDescending(e => e, StringComparer.OrdinalIgnoreCase);
        static IOrderedEnumerable<T> OrderByDescending<T>(this IEnumerable<T> x, Func<T, string> selector) => x.OrderByRand().OrderByDescending(selector, StringComparer.OrdinalIgnoreCase);
        static string Join<T>(this IEnumerable<T> x, string separator = "") => string.Join(separator, x);
        static uint xorshift { get { _xsi.MoveNext(); return _xsi.Current; } }
        static IEnumerator<uint> _xsi = _xsc();
        static IEnumerator<uint> _xsc() { uint x = 123456789, y = 362436069, z = 521288629, w = (uint)(DateTime.Now.Ticks & 0xffffffff); while (true) { var t = x ^ (x << 11); x = y; y = z; z = w; w = (w ^ (w >> 19)) ^ (t ^ (t >> 8)); yield return w; } }
    }
}
namespace Library {
    class LIB_LazySegTree
    {
        public struct SumEntity
        {
            public long s;
            public long c;
        }
        static public LIB_LazySegTree<long, long> CreateRangeUpdateRangeMin(IEnumerable<long> init) => new LIB_LazySegTree<long, long>(init, long.MaxValue, long.MinValue + 100, Math.Min, (x, y) => y, (x, y) => y);
        static public LIB_LazySegTree<long, long> CreateRangeAddRangeMin(IEnumerable<long> init) => new LIB_LazySegTree<long, long>(init, long.MaxValue, 0, Math.Min, (x, y) => x + y, (x, y) => x + y);
        static public LIB_LazySegTree<long, long> CreateRangeUpdateRangeMax(IEnumerable<long> init) => new LIB_LazySegTree<long, long>(init, long.MinValue, long.MaxValue - 100, Math.Max, (x, y) => y, (x, y) => y);
        static public LIB_LazySegTree<long, long> CreateRangeAddRangeMax(IEnumerable<long> init) => new LIB_LazySegTree<long, long>(init, long.MinValue, 0, Math.Max, (x, y) => x + y, (x, y) => x + y);
        static public LIB_LazySegTree<SumEntity, long> CreateRangeUpdateRangeSum(IEnumerable<long> init) => new LIB_LazySegTree<SumEntity, long>(init.Select(e => new SumEntity { s = e, c = 1 }), new SumEntity { c = 0, s = 0 }, long.MaxValue, (x, y) => new SumEntity { c = x.c + y.c, s = x.s + y.s }, (x, y) => new SumEntity { c = x.c, s = x.c * y }, (x, y) => y);
        static public LIB_LazySegTree<SumEntity, long> CreateRangeAddRangeSum(IEnumerable<long> init) => new LIB_LazySegTree<SumEntity, long>(init.Select(e => new SumEntity { s = e, c = 1 }), new SumEntity { c = 0, s = 0 }, 0, (x, y) => new SumEntity { c = x.c + y.c, s = x.s + y.s }, (x, y) => new SumEntity { c = x.c, s = x.s + x.c * y }, (x, y) => x + y);
    }
    class LIB_LazySegTree<T, E> where E : IEquatable<E>
    {
        int n, height, sz;
        T ti;
        E ei;
        Func<T, T, T> f;
        Func<T, E, T> g;
        Func<E, E, E> h;
        T[] dat;
        E[] laz;
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public LIB_LazySegTree(long _n, T _ti, E _ei, Func<T, T, T> _f, Func<T, E, T> _g, Func<E, E, E> _h)
        {
            n = 1; height = 0; sz = (int)_n;
            while (n < _n) { n <<= 1; ++height; }
            ti = _ti;
            ei = _ei;
            f = _f;
            g = _g;
            h = _h;
            dat = Enumerable.Repeat(ti, n << 1).ToArray();
            laz = Enumerable.Repeat(ei, n << 1).ToArray();
            for (var i = n - 1; i > 0; i--) dat[i] = f(dat[(i << 1) | 0], dat[(i << 1) | 1]);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public LIB_LazySegTree(IEnumerable<T> l, T _ti, E _ei, Func<T, T, T> _f, Func<T, E, T> _g, Func<E, E, E> _h) : this(l.Count(), _ti, _ei, _f, _g, _h)
        {
            var idx = 0;
            foreach (var item in l) dat[n + idx++] = item;
            for (var i = n - 1; i > 0; i--) dat[i] = f(dat[(i << 1) | 0], dat[(i << 1) | 1]);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        T Reflect(long i) => laz[i].Equals(ei) ? dat[i] : g(dat[i], laz[i]);
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void Eval(long i)
        {
            if (laz[i].Equals(ei)) return;
            laz[(i << 1) | 0] = h(laz[(i << 1) | 0], laz[i]);
            laz[(i << 1) | 1] = h(laz[(i << 1) | 1], laz[i]);
            dat[i] = Reflect(i);
            laz[i] = ei;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void Thrust(long i)
        {
            for (var j = height; j > 0; j--) Eval(i >> j);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void Thrust(long l, long r)
        {
            if (l == r) { Thrust(l); return; }
            var xor = l ^ r;
            var i = height;
            for (; (xor >> i) != 0; --i) Eval(l >> i);
            for (; i != 0; --i) { Eval(l >> i); Eval(r >> i); }
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void Recalc(long i)
        {
            while ((i >>= 1) > 0) dat[i] = f(Reflect((i << 1) | 0), Reflect((i << 1) | 1));
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        void Recalc(long l, long r)
        {
            var xor = l ^ r;
            while (xor > 1)
            {
                xor >>= 1; l >>= 1; r >>= 1;
                dat[l] = f(Reflect((l << 1) | 0), Reflect((l << 1) | 1));
                dat[r] = f(Reflect((r << 1) | 0), Reflect((r << 1) | 1));
            }
            while (l > 1)
            {
                l >>= 1;
                dat[l] = f(Reflect((l << 1) | 0), Reflect((l << 1) | 1));
            }
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void Update(long l, long r, E v)
        {
            if (l == r) return;
            if (r < l) throw new Exception();
            Thrust(l += n, r += n - 1);
            for (long li = l, ri = r + 1; li < ri; li >>= 1, ri >>= 1)
            {
                if ((li & 1) == 1) { laz[li] = h(laz[li], v); ++li; }
                if ((ri & 1) == 1) { --ri; laz[ri] = h(laz[ri], v); }
            }
            Recalc(l, r);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public T Query(long l, long r)
        {
            if (l == r) return ti;
            if (r < l) throw new Exception();
            Thrust(l += n, r += n - 1);
            var vl = ti; var vr = ti;
            for (long li = l, ri = r + 1; li < ri; li >>= 1, ri >>= 1)
            {
                if ((li & 1) == 1) vl = f(vl, Reflect(li++));
                if ((ri & 1) == 1) vr = f(Reflect(--ri), vr);
            }
            return f(vl, vr);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        int FindToRight(int st, Func<T, bool> check, ref T acc, int k, int l, int r)
        {
            if (l + 1 == r)
            {
                acc = f(acc, Reflect(k));
                return check(acc) ? k - n : sz;
            }
            Eval(k);
            int m = (l + r) >> 1;
            if (m <= st) return FindToRight(st, check, ref acc, (k << 1) | 1, m, r);
            if (st <= l && !check(f(acc, dat[k])))
            {
                acc = f(acc, dat[k]);
                return sz;
            }
            int vl = FindToRight(st, check, ref acc, (k << 1) | 0, l, m);
            if (vl != sz) return vl;
            return FindToRight(st, check, ref acc, (k << 1) | 1, m, r);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public int FindToRight(int st, Func<T, bool> check)
        {
            T acc = ti;
            return FindToRight(st, check, ref acc, 1, 0, n);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        int FindToLeft(int st, Func<T, bool> check, ref T acc, int k, int l, int r)
        {
            if (l + 1 == r)
            {
                acc = f(Reflect(k), acc);
                return check(acc) ? k - n : -1;
            }
            Eval(k);
            int m = (l + r) >> 1;
            if (m > st) return FindToLeft(st, check, ref acc, (k << 1) | 0, l, m);
            if (st >= r - 1 && !check(f(dat[k], acc)))
            {
                acc = f(dat[k], acc);
                return -1;
            }
            int vr = FindToLeft(st, check, ref acc, (k << 1) | 1, m, r);
            if (vr != -1) return vr;
            return FindToLeft(st, check, ref acc, (k << 1) | 0, l, m);
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public int FindToLeft(int st, Func<T, bool> check)
        {
            T acc = ti;
            return FindToLeft(st, check, ref acc, 1, 0, n);
        }
        public T this[long idx]
        {
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            get { Thrust(idx += n); return Reflect(idx); }
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            set { Thrust(idx += n); dat[idx] = value; laz[idx] = ei; Recalc(idx); }
        }
    }
    class LIB_FastIO
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public LIB_FastIO() { str = Console.OpenStandardInput(); }
        readonly Stream str;
        readonly byte[] buf = new byte[1024];
        int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream
        {
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            get { return isEof; }
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        byte read()
        {
            if (isEof) throw new EndOfStreamException();
            if (ptr >= len)
            {
                ptr = 0;
                if ((len = str.Read(buf, 0, 1024)) <= 0)
                {
                    isEof = true;
                    return 0;
                }
            }
            return buf[ptr++];
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        char Char()
        {
            byte b = 0;
            do b = read();
            while (b < 33 || 126 < b);
            return (char)b;
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        virtual public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        virtual public long Long()
        {
            long ret = 0; byte b = 0; var ng = false;
            do b = read();
            while (b != '-' && (b < '0' || '9' < b));
            if (b == '-') { ng = true; b = read(); }
            for (; true; b = read())
            {
                if (b < '0' || '9' < b)
                    return ng ? -ret : ret;
                else ret = ret * 10 + b - '0';
            }
        }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        virtual public double Double() { return double.Parse(Scan(), CultureInfo.InvariantCulture); }
    }
    class LIB_FastIODebug : LIB_FastIO
    {
        Queue<string> param = new Queue<string>();
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        string NextString() { if (param.Count == 0) foreach (var item in Console.ReadLine().Split(' ')) param.Enqueue(item); return param.Dequeue(); }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public LIB_FastIODebug() { }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public override string Scan() => NextString();
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public override long Long() => long.Parse(NextString());
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public override double Double() => double.Parse(NextString());
    }
}