Language: C++

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <numeric>
#include <cstring>
#include <ctime>
#include <cstdlib>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <cmath>
#include <bitset>
#include <casert>
#include <queue>
#include <stack>
#include <deque>
 
  
  
using namespace std;
  
  
template<typename T1, typename T2>inline void chkmin(T1 &x, T2 y) { if (x > y) x = y; }
template<typename T1, typename T2>inline void chkmax(T1 &x, T2 y) { if (x < y) x = y; }
/** Interface */
  
inline int readChar();
template <clas T = int> inline T readInt(); 
template <clas T> inline void writeInt( T x, char end = 0 );
inline void writeChar( int x ); 
inline void writeWord( const char *s );
  
/** Read */
  
static const int buf_size = 4096;
  
inline int getChar() {
    static char buf[buf_size];
    static int len = 0, pos = 0;
    if (pos == len) {
        pos = 0, len = fread(buf, 1, buf_size, stdin);
    }
    if (pos == len) {
        return -1;
    }
    return buf[pos++];
}
  
inline int readChar() {
    int c = getChar();
    while (c <= 32) {
        c = getChar();
    }
    return c;
}
  
template <clas T>
inline T readInt() {
    int s = 1, c = readChar();
    T x = 0;
    if (c == '-')
        s = -1, c = getChar();
    while ('0' <= c && c <= '9')
        x = x * 10 + c - '0', c = getChar();
    return s == 1 ? x : -x;
}
  
/** Write */
  
static int write_pos = 0;
static char write_buf[buf_size];
  
inline void writeChar( int x ) {
    if (write_pos == buf_size)
        fwrite(write_buf, 1, buf_size, stdout), write_pos = 0;
    write_buf[write_pos++] = x;
}
  
template <clas T> 
inline void writeInt( T x, char end ) {
    if (x < 0)
        writeChar('-'), x = -x;
  
    char s[24];
    int n = 0;
    while (x || !n)
        s[n++] = '0' + x % 10, x /= 10;
    while (n--)
        writeChar(s[n]);
    if (end)
        writeChar(end);
}
  
inline void writeWord( const char *s ) {     while (*s)
writeChar(*s++); }
  
struct Flusher {
    ~Flusher() {
        if (write_pos)
            fwrite(write_buf, 1, write_pos, stdout), write_pos = 0;
    }
} flusher;
  
using namespace std;


#define sz(c) (int)(c).size()
#define all(c) (c).begin(), (c).end()
const int MAXN = 300011;
const int INF = 1000000001;


struct segment
{   
    int a, b;
};


int lc[MAXN], rc[MAXN], lb[MAXN], rb[MAXN];
int tot;
vector<int> b[MAXN];
int intr[MAXN], ins[MAXN];
segment s[MAXN];


bool comp(segment a, segment b) {
    return a.a < b.a;
}

 
int build(int l, int r) {
    int t = ++ tot;
    lb[t] = l; rb[t] = r;
    if (l < r)  {
        lc[t] = build(l, (l + r) / 2);
        rc[t] = build((l + r) / 2 + 1, r);
    } else {
        intr[s[l].b] = t;
    }
    return t;
}


void rmq(int t, int l, int r, int d) {
    if (l > r) {
        return;
    }
    if (l <= lb[t] && rb[t] <= r) {
        b[d].push_back(t);
        return;
    }
    if (l <= rb[lc[t]]) {
        rmq(lc[t], l, r, d);
    }
    if (r >= lb[rc[t]]) {
        rmq(rc[t], l, r, d);
    }
}
 
 
int uk, used[MAXN], low[MAXN], shed[MAXN], inshed[MAXN], top, cnt;
int ini[MAXN];



void init() {
    uk = 0;
    for (int i = 1; i <= tot * 2; i++) {
        used[i] = low[i] = shed[i] = inshed[i] = ini[i] = 0;
    }
    top = cnt = 0;
}


void dfs(int t) {
    used[t] = low[t] = ++uk; 
    shed[++top] = t; 
    inshed[t] = 1;
    for (int i = 0; i < (int)b[t].size(); i++)
        if (!used[b[t][i]]) {
            dfs(b[t][i]);
            low[t] = min(low[b[t][i]], low[t]);
        } else if (inshed[b[t][i]]) {
            low[t] = min(used[b[t][i]], low[t]);
        }
 
    if (low[t] == used[t]) {
        int p; 
        cnt++;
        do {
            p = shed[top--];
            inshed[p] = 0;
            ini[p] = cnt;
        }
        while (p != t);
    }
}
 

int n;
int a[MAXN];


int main() {
    n = readInt();
    for (int i = 1; i <= n; i++) {
        a[i] = readInt(), a[i + n] = readInt();
    }
    for (int i = 1; i <= n * 2; i++) {
        s[i] = (segment){a[i], i};
    }
    sort(s + 1, s + n * 2 + 1, comp);
    for (int i = 1; i <= n * 2; i++) {
        ins[s[i].b] = i;
    }
    build(1, n * 2);
    int l = 0, r = s[n * 2].a;
    while (l < r) {
        int mid = (l + r + 1) >> 1;
        for (int i = 1; i <= tot * 2; i++) {
            b[i].clear();
        }
        for (int i = 1; i <= tot; i++) {
            if (lc[i] || rc[i]) {
                b[i].push_back(lc[i]),
                b[i].push_back(rc[i]);
            }
        }
        for (int i = 1; i <= n * 2; i++) {
            int r = lower_bound(s + 1, s + n * 2 + 1, (segment){a[i] + mid, 0}, comp) - s - 1,
                l = upper_bound(s + 1, s + n * 2 + 1, (segment){a[i] - mid, 0}, comp) - s;
            rmq(1, l, ins[i] - 1, intr[i <= n? i + n: i - n]);
            rmq(1, ins[i] + 1, r, intr[i <= n? i + n: i - n]);
        }
        init();
        for (int i = 1; i <= tot * 2; i++) {
            if (!ini[i]) {
                dfs(i);
            }
        }
        bool good = 1;
        for (int i = 1; i <= n; i++) {
            if (ini[intr[i]] == ini[intr[i + n]]) {
                good = 0;
                break;
            }
        }
        if (good) {
            l = mid;
        } else {
            r = mid - 1;
        }
    }
    writeInt(l, '\n');
    return 0;
}


Compiler output:
a.cc:17:10: fatal error: casert: No such file or directory
   17 | #include <casert>
      |          ^~~~~~~~
compilation terminated.