【例题 6-15 UVA

【链接】 我是链接,点我呀:)
【题意】

在这里输入题意

【题解】

拓扑大水题

【代码】

#include <bits/stdc++.h>
using namespace std;

const int N = 100;
int n,m;
int du[N+10];
vector <int> g[N+10];
queue <int> dl;

int main(){
//	freopen("rush.txt","r",stdin);
    while (~scanf("%d%d",&n,&m)){
        if (n==0 && m==0) break;
        while (!dl.empty()) dl.pop();
        for (int i = 1;i <= N;i++) g[i].clear(),du[i] = 0;
        for (int i = 1;i <= m;i++){
            int x,y;
            scanf("%d%d",&x,&y);
            g[x].push_back(y);
            du[y]++;
        }
        for (int i = 1;i <= n;i++)
            if (du[i]==0){
                dl.push(i);
                du[i] = -1;
            }
        vector <int> v;
        while (!dl.empty()){
            int x = dl.front();
            v.push_back(x);
            dl.pop();
            for (int y:g[x]){
                du[y]--;
                if (du[y]==0){
                    du[y] = -1;
                    dl.push(y);
                }
            }
        }
        int first = 1;
        for (int x:v){
            if (!first) putchar(' ');
            first = 0;
            printf("%d",x);
        }
        puts("");
    }
    return 0;
}