HDU 1285 确定比赛名次 拓扑排序

题目链接

http://acm.hdu.edu.cn/showproblem.php?pid=1285

思路

输入的数据一定有解：拓扑排序，优先取出编号小的点。

#include<cstdio>#include<queue>#include<iostream>#include<functional>#include<vector>#include<map>#include<cstring>#include<string>#include<set>#include<stack>#include<algorithm>#define cle(a) memset(a,0,sizeof(a))#define inf(a) memset(a,0x3f,sizeof(a))#define ll long long#define Rep(i,a,n) for(int i=a;i<=n;i++)using namespace std;#define INF2 9223372036854775807llconst int INF = ( 2e9 ) + 2;const ll maxn = 510;vector<int> g[maxn];int In[maxn];void topsort(int n){    priority_queue<int,vector<int>,greater<int> > q;    for(int i=1;i<=n;i++)    if(In[i]==0)q.push(i);    int cnt=0;    while(!q.empty())    {        int u=q.top();q.pop();        for(int i=0,L=g[u].size();i<L;i++)        {            int v=g[u][i];            In[v]--;            if(In[v]==0)            q.push(v);        }        if(cnt!=n-1)        printf("%d ",u);        else        printf("%d\n",u);        cnt++;    }}int main(){    int n,m;    while(~scanf("%d%d",&n,&m))    {        memset(In,0,sizeof(In));        for(int i=0;i<=n;i++)g[i].clear();        for(int i=0;i<m;i++)        {            int u,v;            scanf("%d%d",&u,&v);            g[u].push_back(v);            In[v]++;        }        topsort(n);    }}