备战NOIP——模板复习7

这里只有模板，并不作讲解，仅为路过的各位做一个参考以及用做自己复习的资料，转载注明出处。

Tarjan模板

/*Copyright: Copyright (c) 2018
*Created on 2018-10-30 
*Author: 十甫
*Version 1.0 
*Title: tarjan
*Time: 9.5 mins but 1 big mistake
*/
#include<cstdio>
#include<iostream>
#include<stack>
using namespace std;
const int size = 100005;

int head[size];
struct edge {
	int to, next;
} data[size];
inline void add_edge(int from, int to, int i) {
	data[i] = (edge) {to, head[from]};
	head[from] = i;
}

int belong[size], dfn[size], low[size];
stack <int> sta;

void dfs(int pos, int &ord) {
	sta.push(pos);
	dfn[pos] = low[pos] = ord;
	for(int i = head[pos];i;i = data[i].next) {
		int u = data[i].to;
		if(dfn[u]) {
			low[pos] = min(low[pos], dfn[u]);
		} else {
			dfs(u, ++ord);
		}
		low[pos] = min(low[pos], low[u]);
	}
	if(low[pos] == dfn[pos]) {
		belong[pos] = ++belong[0];
		while(sta.top() != pos) {
			belong[sta.top()] = belong[0];
			sta.pop();
		}
		sta.pop();
	}
}


void tarjan(int n) {
	for(int i = 1;i <= n;i++) {
		if(!dfn[i]) {
			int ord = 1;
			dfs(i, ord);
		}
	}
	for(int i = 1;i <= n;i++) {
		printf("%d ", belong[i]);
	}
	printf("
");
	return;
}

int main() {
	int n, m;
	scanf("%d%d", &n, &m);
	for(int i = 1;i <= m;i++) {
		int a, b;
		scanf("%d%d", &a, &b);
		add_edge(a, b, i);
	}
	tarjan(n);
	return 0;
}