uva 10305 Ordering Tasks (拓扑排序)

uva  10305  Ordering Tasks (拓扑排序)

这题用到的时最简单的拓扑排序，先建立大小关系的邻接矩阵，再拓扑排序

#include <iostream>
#include <queue>
#include <vector>
#include <cstdio>
using namespace std;

const int maxn=110;
bool a[maxn][maxn];
int degree[maxn],n,m;

void initial(){
	for(int i=0;i<=n;i++){
		degree[i]=0;
		for(int j=0;j<=n;j++){
			a[i][j]=false;
		}
	}
}

void input(){
	int u,v;
	while(m-- >0){
		scanf("%d%d",&u,&v);
		degree[v]++;
		a[u][v]=true;
	}
}

void solve(){
	int s;
	vector <int> v; 
	queue <int> q;
	for(int i=1;i<=n;i++){
		if(degree[i]==0){
			q.push(i);
		}
	}
	while(!q.empty()){
		s=q.front();
		q.pop();
		v.push_back(s);
		for(int i=1;i<=n;i++){
			if(a[s][i]){
				degree[i]--;
				if(degree[i]==0){
					q.push(i);
				}
			}
		}
	}
	if(v.size()>0) printf("%d",v[0]);
	for(int i=1;i<v.size();i++){
		printf(" %d",v[i]);
	}
	cout<<endl;
}

int main(){
	while(scanf("%d%d",&n,&m)!=EOF && (n||m)){
		initial();
		input();
		solve();
	}
	return 0;
}