洛谷P3063 [USACO12DEC]牛奶的路由Milk Routing

链接

其实在博客园里写题解都挺应付的都是在洛谷写了之后

挑一部分粘过来

在洛谷写的也都是废话，是为了凑篇幅

主要就是代码

大体思路就一提

这题贪心不行废话

跑m遍SPFA更新最小值

注意数组记得清空

The Last:

#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = ;
int cnt, head[N << ], n, m, x, minn = 0x3f3f3f3f, C[N], t, s, dis[N];
bool vis[N];
struct node{
    int nxt, to, d, w;
}e[N << ];
int read() {
    int s = , w = ;
    char ch = getchar();
    while(!isdigit(ch)) {if(ch == '-') w = -; ch = getchar();}
    while(isdigit(ch)) {s = s *  + ch - ''; ch = getchar();}
    return s * w;
}
void add(int x, int y, int w, int d) {
    e[++cnt].nxt = head[x];
    e[cnt].to = y;
    e[cnt].w = w;
    e[cnt].d = d;
    head[x] = cnt;
}
void spfa (int ww) {
    queue<int> q;
    memset(dis, , sizeof(dis));
    memset(vis, , sizeof(vis));
    vis[] = ;
    q.push();
    dis[] = ;
    while (!q.empty()) {
        int he = q.front();
        q.pop();
        vis[he] = ;
        for (int i = head[he]; i ;i = e[i].nxt) {
            if (dis[e[i].to] > dis[he] + e[i].d && e[i].w >= ww) {
                dis[e[i].to] = dis[he] + e[i].d;
                if (!vis[e[i].to]) {
                    vis[e[i].to] = ;
                    q.push(e[i].to);
                }
            }
        }
    }
}
int main() {
    n = read(), m = read(), x = read();
    for(int i = ; i <= m; i++) {
        int x, y, d, l;
        x = read(), y = read(), d = read(), l = read();
        add(x, y, l, d), add(y, x, l, d);
        C[i] = l;
    }
//    for(int i = 1; i <= n; i++)
//        printf("%d ", e[i].w);
//    printf("\n");
//    sort(C + 1, C + 1 + m);
    for(int i = ; i <= m; i++) {
        spfa(C[i]);
        minn = min(minn, (dis[n] + x / C[i]));
    }
//    for(int i = 1; i <= n; i++)
//        printf("%d ", dis[i]);
//    printf("\n");
    printf("%d\n", minn);
    return ;
}

谢谢收看，祝身体健康！