Submission #63801894

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Source Code Expand

//People who believe in miracles are as amazing as miracles themselves.
#include<bits/stdc++.h>
#define ll long long
using namespace std;
inline ll read(){
    ll x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-') f=-f;ch=getchar();}
    while(ch>='0'&&ch<='9')x=(x<<3)+(x<<1)+(ch^48),ch=getchar();
    return x*f;
}

const int N=3e5+10;
int n,k,f[N];

vector<int> G[N];

void dfs(int x,int fa){
    vector<int> vc;
    for(int y:G[x]) if(y!=fa){
        dfs(y,x);
        if(f[y]) vc.emplace_back(f[y]);
    }
    switch(vc.size()){
        case 0:
            f[x]=1;
            return;
        case 1:
            if(vc[0]==k-1){
                f[x]=0;
                return;
            }
            f[x]=vc[0]+1;
            return;
        case 2:
            if(vc[0]+vc[1]+1==k){
                f[x]=0;
                return;
            }
            puts("No"),exit(0);
        default:
            puts("No"),exit(0);
    }
}

inline void solve(){
    n=read(),k=read();
    if(k==1) return puts("Yes"),void();
    for(int u,v,i=1;i<n*k;++i){
        u=read(),v=read();
        G[u].emplace_back(v),G[v].emplace_back(u);
    }
    dfs(1,0),puts("Yes");
}

signed main(){
#ifndef ONLINE_JUDGE
    freopen("../1.in","r",stdin);
    freopen("../1.out","w",stdout);
#endif
    return solve(),0;
}

Submission Info

Judge Result