UVa 10305 Ordering Tasks【拓扑排序】

题意：给出n件事情，m个二元组关系，求它们的拓扑序列

 

用的队列来做

#include<iostream>  
#include<cstdio>  
#include<cstring> 
#include <cmath> 
#include<stack>
#include<vector>
#include<map> 
#include<set>
#include<queue> 
#include<algorithm>  
using namespace std;

#define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)

typedef long long LL;
const int INF = (1<<30)-1;
const int mod=1000000007;
const int maxn=100005;
int ecnt;
int n,m;

int g[1005][1005],in[1005],ans[maxn];

void toposort(){
    queue<int> q;
    
    for(int i=1;i<=n;i++)
    if(in[i]==0) q.push(i);
    
    int cnt=0;
    while(!q.empty()){
        int tmp=q.front();q.pop();
        ans[++cnt]=tmp;
        
        for(int j=1;j<=n;j++){
            if(g[tmp][j]){
                in[j]--;
                if(in[j]==0) q.push(j);
            }
        }        
    }
    
    printf("%d",ans[1]);
    for(int i=2;i<=cnt;i++)
    printf(" %d",ans[i]);    
    printf("\n");
}


int main(){
    while(scanf("%d %d",&n,&m)!=EOF){
        if(n==0&&m==0) break;
        
        memset(g,0,sizeof(g));
        memset(in,0,sizeof(in));
        
        while(m--){
            int u,v;
            cin>>u>>v;
            g[u][v]=1;
            in[v]++;
        }
        toposort();
    }
    return 0;        
}