Programación Competitiva

#include <bits/stdc++.h>
using namespace std;
struct Node {
    int x, y, v;// x->y, v
    int next;
} edge[50005];
int e, head[1005], dis[1005], previ[1005], record[1005];
void addEdge(int x, int y, int v) {
    edge[e].x = x, edge[e].y = y, edge[e].v = v;
    edge[e].next = head[x], head[x] = e++;
    edge[e].x = y, edge[e].y = x, edge[e].v = 0;
    edge[e].next = head[y], head[y] = e++;
}
int maxflow(int s, int t) {
    int flow = 0;
    int i, j, x, y;
    while(1) {
        memset(dis, 0, sizeof(dis));
        dis[s] =  0xffff; // oo
        queue<int> Q;
        Q.push(s);
        while(!Q.empty()) {
            x = Q.front();
            Q.pop();
            for(i = head[x]; i != -1; i = edge[i].next) {
                y = edge[i].y;
                if(dis[y] == 0 && edge[i].v > 0) {
                    previ[y] = x;
                    record[y] = i;
                    dis[y] = std::min(dis[x], edge[i].v);
                    Q.push(y);
                }
            }
            if(dis[t])  break;
        }
        if(dis[t] == 0) break;
        flow += dis[t];
        for(x = t; x != s; x = previ[x]) {
            int ri = record[x];
            edge[ri].v -= dis[t];
            edge[ri^1].v += dis[t];
        }
    }
    return flow;
}
 
int main() {
    int cases; scanf("%d",&cases);
    while(cases--) {
        e=0;
        memset(head, -1, sizeof(head));
        int s = 240, t = 241, c, x, y;
        cin >> c;
        while(c--) {
            cin >> x >> y;
            addEdge(x, y+120, 1);
        }
        for(int i=0; i<120;i++){
            addEdge(s, i, 1);
            addEdge(120+i, t, 1);
        }
        int flow = maxflow(s, t);
        cout << flow <<"\n";
    }
    return 0;
}