给任务排序(Ordering Tasks,UVa 10305)

原题链接

分析：拓扑排序

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<vector>
#include<string>
#include<map>
#include<cmath>
#include<sstream>
#include<queue>
#include<cctype>
using namespace std;
typedef long long ll;
#define MAX 105
int G[MAX][MAX];
int vis[MAX];
int ans[MAX];
int m,n,t;
bool dfs(int u) {
vis[u] = -1;
for(int v=1;v<=n;v++)
if(G[u][v])
if(!vis[v] && !dfs(v)) return false;
ans[t--] = u;
vis[u] = 1;
return true;
}
bool toposort() {
memset(vis,0,sizeof(vis));
for(int u=1;u<=n;u++) if(!vis[u])
if(!dfs(u)) return false;
return true;
}
int main() {
while(~scanf("%d%d",&n,&m) && (n || m)) {
memset(G,0,sizeof(G));
int a,b;
for(int i=0;i<m;i++) {
scanf("%d%d",&a,&b);;
G[a][b] = 1;
}
t = n;
toposort();
for(int i=1;i<=n;i++) i == n?printf("%d\n",ans[i]):printf("%d ",ans[i]);
}
return 0;
}