【HDOJ】3592 World Exhibition

基础差分约束。

/* 3592 */
#include <iostream>
#include <algorithm>
#include <queue>
#include <vector>
#include <cstdio>
#include <cstring>
using namespace std;

#define MAXN 1005
#define MAXE 20005
#define INF     0x3f3f3f3f

typedef struct {
    int v, w, next;
} Edge_t;

Edge_t E[MAXE];
int head[MAXN], L;
int dis[MAXN], deg[MAXN];
bool visit[MAXN];
int n, x, y;

void addEdge(int u, int v, int w) {
    E[L].v = v;
    E[L].w = w;
    E[L].next = head[u];
    head[u] = L++;
}

void init() {
    memset(head, -1, sizeof(int)*(n+1));
    memset(dis, 0x3f, sizeof(int)*(n+1));
    memset(deg, 0, sizeof(int)*(n+1));
    memset(visit, false, sizeof(bool)*(n+1));
    L = 0;
}

int spfa() {
    int i, j, k;
    int u, v, w;
    queue<int> Q;
    
    deg[1] = 1;
    visit[1] = true;
    dis[1] = 0;
    Q.push(1);
    
    while (!Q.empty()) {
        u = Q.front();
        Q.pop();
        visit[u] = false;
        for (i=head[u]; i!=-1; i=E[i].next) {
            v = E[i].v;
            w = E[i].w;
            if (dis[v] > dis[u] + w) {
                dis[v] = dis[u] + w;
                if (!visit[v]) {
                    visit[v] = true;
                    Q.push(v);
                    if (++deg[v] > n)
                        return -1;
                }
            }
        }
    }
    if (dis[n] == INF)
        return -2;
    else
        return dis[n];
}

int main() {
    int t;
    int i, j, k;
    
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    scanf("%d", &t);
    while (t--) {
        scanf("%d %d %d", &n, &x, &y);
        init();
        while (x--) {
            scanf("%d %d %d", &i, &j, &k);
            addEdge(i, j, k);
        }
        while (y--) {
            scanf("%d %d %d", &i, &j, &k);
            addEdge(j, i, -k);
        }
        k = spfa();
        printf("%d
", k);
    }
    
    return 0;
}