codeforces 510c Fox And Names 拓扑排序

标签：拓扑排序

#include <cstdio>
#include <cstring>
#include <iostream>
#include <queue>
using namespace std;
int t;
int ma[30][30];
char a[105][105];
void tpusort(){
	int d[30];
	queue<int> que;
	queue<int> ans;
	int dd = 0;
	for(int i = 0;i < 26;i++){
		int cc = 0;
		for(int j = 0;j < 26;j++){
			cc += ma[j][i];	
		}
		d[i] = cc;
		if(cc == 0){
			que.push(i);
		}
	
	}
	while(!que.empty()){
		int tm = que.front();
		que.pop();
		ans.push(tm);
		for(int i = 0;i < 26;i++){
			if(ma[tm][i] == 1){
				ma[tm][i] = 0;
				d[i]--;
				if(d[i] == 0){
					que.push(i);
				}
			}
		}
	}
	if(ans.size() == 26){
		while(!ans.empty()){
			int tm = ans.front();
			ans.pop();
			putchar(tm+'a');
		}
		printf("\n");
	}
	else{
		printf("Impossible\n");
	}
}

int main(){
	scanf("%d",&t);
	memset(ma,0,sizeof(ma));
			
	for(int i = 0;i < t;i++){
		scanf("%s",a[i]);
	}
	
	int flag = 1;

	for(int i = 0;i < t;i++){
		for(int j = 0;j < i;j++){
			for(int k = 0;a[j][k];k++){
				if(a[i][k] == '\0'){
					flag = 0;
					break;
				}
				if(a[i][k] != a[j][k]){
					ma[a[j][k]-'a'][a[i][k]-'a'] = 1;
					break;
				}
				
			}
		}
	}
	if(flag){
		tpusort();
	}
	else{
		printf("Impossible\n");
	}
	return 0;
}

codeforces 510c Fox And Names 拓扑排序

标签：拓扑排序

原文地址：http://blog.csdn.net/qq_24667639/article/details/46041203