HDU1827 Summer Holiday 强连通 Tarjan 缩点 统计

中文题一道，好题啊，读题简单多了，做起来也不难，就是缩点，缩点完成后，入度为0的点 就是需要主人公特意需要去打电话的点，缩点后 对于某一个团的最小话费就很好求了，直接暴力查找就可以了，

#include<iostream>#include<cstdio>#include<list>#include<algorithm>#include<cstring>#include<string>#include<queue>#include<stack>#include<map>#include<vector>#include<cmath>#include<memory.h>#include<set>#define ll long long#define eps 1e-7#define inf 0xfffffffconst ll INF = 1ll<<61;using namespace std;//vector<pair<int,int> > G;//typedef pair<int,int > P;//vector<pair<int,int> > ::iterator iter;////map<ll,int >mp;//map<ll,int >::iterator p;//typedef struct Node {int from,to;int nex;};Node edge[1000 * 10];int head[2000 + 10],Stack[2000 + 10],low[2000 + 10],dfn[2000 + 10],id[2000 + 10],w[1000 + 10];bool vis[2000 + 10];int tot,vis_num,stack_num,scc_num;void clear() {memset(head,-1,sizeof(head));memset(Stack,0,sizeof(Stack));memset(low,0,sizeof(low));memset(dfn,-1,sizeof(dfn));memset(id,0,sizeof(id));memset(vis,false,sizeof(vis));memset(w,0,sizeof(w));memset(edge,0,sizeof(edge));tot = 0;vis_num = 0;stack_num = 0;scc_num = 0;}void addedge(int u,int v) {edge[tot].from = u;edge[tot].to = v;edge[tot].nex = head[u];head[u] = tot++;}void tarjan(int v) {dfn[v] = low[v] = ++vis_num;vis[v] = true;Stack[stack_num++] = v;for(int i=head[v];i!=-1;i=edge[i].nex) {int u = edge[i].to;if(dfn[u] == -1) {tarjan(u);low[v] = min(low[u],low[v]);}else if(vis[u])low[v] = min(low[v],dfn[u]);}int tmp;if(low[v] == dfn[v]) {scc_num++;do {tmp = Stack[--stack_num];id[tmp] = scc_num;vis[tmp] = false;}while(tmp != v);}}void cal(int n) {for(int i=1;i<=n;i++)if(dfn[i] == -1)tarjan(i);}int main() {int n,m;while(scanf("%d %d",&n,&m) == 2) {clear();for(int i=1;i<=n;i++)scanf("%d",&w[i]);int a,b;while(m--) {scanf("%d %d",&a,&b);addedge(a,b);}cal(n);int in[2000 + 10];//入度int hehe[2000 + 10];//话费memset(in,0,sizeof(in));for(int i=0;i<tot;i++) {int u = edge[i].from,v = edge[i].to;if(id[u] != id[v])in[ id[v] ]++;}int ans1 = 0;for(int i=1;i<=scc_num;i++) {if(in[i] == 0)ans1++;hehe[i] = inf;}for(int i=1;i<=n;i++) {int tmp = id[i];if(in[tmp] == 0)hehe[tmp] = min(hehe[tmp],w[i]);}int ans2 = 0;for(int i=1;i<=scc_num;i++)if(hehe[i] != inf)ans2 += hehe[i];printf("%d %d\n",ans1,ans2);}returnEXIT_SUCCESS;}