Luogu1137 旅行计划(拓扑排序)

Posted 2021-01-03 ubospica

题目传送门

拓扑排序板子题，模拟即可。

代码

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<set>
#include<map>
using namespace std;
#define rep(i,l,r) for(register int i=(l);i<=(r);++i)
#define repdo(i,l,r) for(register int i=(l);i>=(r);--i)
#define il inline
typedef double db;
typedef long long ll;

//---------------------------------------
const int nsz=100050,msz=200050;
int n,m;
struct te{int t,pr;}edge[msz];
int hd[nsz],pe=1,in[nsz];
void adde(int f,int t){edge[++pe]=(te){t,hd[f]};hd[f]=pe;}

int que[nsz],qh=1,qt=0;
int ts[nsz],pt=0;
bool topsort(){
    rep(i,1,n)if(in[i]==0)que[++qt]=i,ts[++pt]=i;
    while(qh<=qt){
        int u=que[qh++];
        for(int i=hd[u],v=edge[i].t;i;i=edge[i].pr,v=edge[i].t){
            --in[v];
            if(in[v]==0)ts[++pt]=v,que[++qt]=v;
        }
    }
    return pt==n;
}
int dp[nsz];
void getdp(){
    rep(i,1,n)dp[i]=1;
    rep(p,1,pt){
        for(int i=hd[ts[p]],v=edge[i].t;i;i=edge[i].pr,v=edge[i].t){
            dp[v]=max(dp[v],dp[ts[p]]+1);
        }
    }
}

int main(){
    ios::sync_with_stdio(0),cin.tie(0);
    cin>>n>>m;
    int a,b;
    rep(i,1,m)cin>>a>>b,adde(a,b),++in[b];
    topsort();
    //rep(i,1,pt)printf("%d ",ts[i]);
    getdp();
    rep(i,1,n)cout<<dp[i]<<'
';
    return 0;
}














//  freopen(".in","r",stdin);
//  freopen(".out","w",stdout);