Problem:
Range Sum Query

Write a program which manipulates a sequence A = {a1, a2, . . . , an} with the following operations:

add(i, x): add x to ai.

getSum(s, t): print the sum of as, as+1,...,at.

Note that the initial values of ai (i = 1, 2, . . . , n) are 0.

Input

n q
com1 x1 y1
com2 x2 y2
...
comq xq yq

In the first line, n (the number of elements in A) and q (the number of queries) are given. Then, q queries are given where com represents the type of queries. '0' denotes add(xi, yi) and '1' denotes getSum(xi, yi).

Output

For each getSum operation, print the sum in a line.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 100000

If comi is 0, then 1 ≤ xi ≤ n, 0 ≤ yi ≤ 1000.

If comi is 1, then 1 ≤ xi ≤ n, 1 ≤ yi ≤ n.

Sample Input 1

3 5
0 1 1
0 2 2
0 3 3
1 1 2
1 2 2

Sample Output 1

3
2

Solution in C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static int[] segment;
        static int size;

        static void Main(string[] args)
        {
            string[] input1 = Console.ReadLine().Split(' ');
            int n = int.Parse(input1[0]);
            int q = int.Parse(input1[1]);

            Init(n);

            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < q; i++)
            {
                string[] input2 = Console.ReadLine().Split(' ');
                int c = int.Parse(input2[0]);
                int x = int.Parse(input2[1]);
                int y = int.Parse(input2[2]);

                if (c == 0) Update(x - 1, y);
                else
                {
                    sb.AppendLine(Query(x - 1, y, 0, 0, size).ToString());
                }
            }
            Console.Write(sb);
        }

        static void Init(int n)
        {
            size = 1;

            while (size < n) size *= 2;

            segment = new int[2 * size];
        }

        static void Update(int i, int a)
        {
            i += size - 1;
            segment[i] += a;

            while (i > 0)
            {
                i = (i - 1) / 2;
                segment[i] += a;
            }
        }

        static int Query(int a, int b, int k, int l, int r)
        {
            if (r <= a || b <= l) return 0;

            if (a <= l && r <= b) return segment[k];
            else
            {
                int vl = Query(a, b, k * 2 + 1, l, (l + r) / 2);
                int vr = Query(a, b, k * 2 + 2, (l + r) / 2, r);

                return vl + vr;
            }
        }
    }
}