HDU1350 - Taxi Cab Scheme

#include <cstring>
#include <iostream>
#include <cstdlib>
#include <cctype>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <queue>
#define INF (int)(1e9)
#define maxn 1010
using namespace std;
typedef long long ll;
int uN, vN;//u,v数目
int edge[maxn][maxn];
int linker[maxn];
bool used[maxn];
bool dfs(int u) { //从左边开始找增广路径
    int v;
    for(v = 0; v < vN; ++ v) {
        if(edge[u][v] && !used[v]) {
            used[v] = true;
            if(linker[v] == -1 || dfs(linker[v])) {
                //找增广路，反向
                linker[v] = u;
                return true;
            }
        }
    }
    return false;
}
int max_match() {
    int res=0;
    int u;
    memset(linker,-1,sizeof(linker));
    for(u = 0; u < uN; u++) {
        memset(used, 0, sizeof(used));
        if(dfs(u)) res ++;
    }
    return res;
}
struct Node {
    int t, cost,a,b,c,d;
}cab[maxn];
int main() {
    int t;
    scanf("%d", &t);
    while (t --) {
        memset(edge, 0, sizeof(edge));
        int n, a, b, c, d;
        string time;
        scanf("%d", &n);
        for (int i = 0; i < n; ++ i) {
            cin >> time;
            scanf("%d%d%d%d", &a, &b, &c, &d);
            cab[i].t = ((time[0]- '0')*10+time[1]-'0')*60+((time[3]- '0')*10+time[4]-'0');
            cab[i].cost = abs(a-c) + abs(b-d);
            cab[i].a=a,cab[i].b=b,cab[i].c=c,cab[i].d=d;
        }
        for (int i = 0; i < n; ++ i) {
            for (int j = i+1; j < n; ++ j) {
                if (cab[i].t + cab[i].cost + abs(cab[i].c-cab[j].a) + abs(cab[i].d-cab[j].b) < cab[j].t) {
                    edge[i][j] = 1;
                }
            }
        }
        uN = vN = n;
        cout << n - max_match() << endl;
    }
}