codevs1506傳話（tarjan）_tarjan

這個題多種解法，我用tarjan又寫了一遍

#include <cstdio>#include <iostream>#include <cstring>#include <algorithm>#include <stack>using namespace std;const int MAXN = 2000;int n,m,to[MAXN<<1],head[MAXN],cd[MAXN],blt[MAXN],nxt[MAXN<<1],tot,scc[MAXN],sz[MAXN],tim=0;bool vis[MAXN],flag = 0;struct Edge{    int from,to;}e[MAXN<<1];stack <int> s;void build(int f,int t){    to[++tot] = t;    nxt[tot] = head[f];    head[f]  = tot;}int low[MAXN],dfn[MAXN],scccnt = 0; void dfs(int u){    low[u] = dfn[u] = ++tim;    s.push(u);    int v;    for(int i = head[u] ; i ; i = nxt[i])    {        v = to[i];        if(!dfn[v])        {            dfs(v);            low[u] = min(low[u],low[v]);        }        else if(!scc[v])        {            low[u] = min(low[u],dfn[v]);        }    }    if(low[u] == dfn[u])    {        int x;        scccnt ++;        while(!s.empty())        {            x = s.top();            s.pop();            scc[x] = scccnt;            sz[scccnt]++;            if(u == x)            break;        }    }}int main(){    scanf("%d%d",&n,&m);    for(int i = 1; i <= m; i ++)    {        scanf("%d%d",&e[i].from ,& e[i].to);        build(e[i].from ,e[i].to);    }    for(int i = 1; i <= n; i ++)    if(!dfn[i])    dfs(i);    int ans = 0,q = 0;    int xx[5000];    for(int i = 1; i <= scccnt ; i ++)    {        if(sz[i]>1)        {            q ++;            xx[q] = i;        }    }    for(int j = 1; j <= q; j ++)    for(int i = 1; i <= n; i ++)    {        if(scc[i] == xx[j])        {            vis[i] = 1;        }    }    for(int i = 1; i <= n; i ++)    {        if(vis[i])        puts("T");        else        puts("F");    }    return 0;}