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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#688330#9530. A Game On TreedoyoWA 3ms5752kbC++202.2kb2024-10-30 03:59:572024-10-30 03:59:58

Judging History

This is the latest submission verdict.

  • [2024-10-30 03:59:58]
  • Judged
  • Verdict: WA
  • Time: 3ms
  • Memory: 5752kb
  • [2024-10-30 03:59:57]
  • Submitted

answer

#include<bits/stdc++.h>
using namespace std;
#define FOR(i,j,k) for(int i=j;i<=k;++i)
#define For(i,j,k) for(int i=j;i>=k;--i)
#define int long long
const int N = 1e5 + 111;
const int Mod = 998244353;
vector<int> e[N];
int ans;
int f[N],fl[N],fll[N],h[N],tmp[N];
int totsize[N];
int sz[N];
int ksm(int x,int y){
	int ans = 1;
	while(y){
		if(y&1) ans = ans * x % Mod;
		y>>=1,x=x*x%Mod;
	}
	return ans;
}
int inv(int x){return ksm(x,Mod-2);}
void get_size(int x,int fa){
	totsize[x] = 1;
	for(auto nxt:e[x])if(nxt!=fa){
		get_size(nxt,x);
		totsize[x] += totsize[nxt];
	}
}

void dfs(int x,int fa){
	sz[x] = 1;
	f[x] = 1;
	for(auto nxt:e[x])if(nxt!=fa){
		dfs(nxt,x);
		int g = (f[nxt] + sz[nxt]*2);
		int gl = fl[nxt] + f[nxt];
		int gll = fll[nxt] + 2*fl[nxt] + f[nxt];
		//和其它子树跨根贡献 
		ans += g * fll[x] + f[x] * gll + 2 * fl[x] * gl;
		ans %= Mod;
		//自己子树内一条到根x,一条不到根x的贡献
		//自己内部那一条到x的可以连出去 
		h[x] += (tmp[nxt] + h[nxt])%Mod * (totsize[x]-sz[nxt])%Mod,h[x] %= Mod;
		f[x] += g;
		f[x] += 2 * ((sz[x]-1) * sz[nxt]);//要求必须有一个在nxt中 
		f[x] %= Mod;
		fl[x] += gl,fl[x] %= Mod;
		fll[x] += gll,fll[x] %= Mod;
		//tmp 计算一条往上延申,另一条不选择往上延申的方案数,要求两条都是过 x 点的
		//用于下一步的计算 
		tmp[x] += gll * 2 * (totsize[x]-sz[nxt]);
		tmp[x] %= Mod;
		sz[x] += sz[nxt];
	}
	ans += h[x];
	h[x] %= Mod;
}
void sol(){
	int n;
	cin>>n;
	FOR(i,1,n-1){
		int x,y;
		cin>>x>>y;
		e[x].push_back(y);
		e[y].push_back(x);
	}
	ans = 0;
	get_size(1,0);
	dfs(1,0);
	int iv = inv(n*(n-1)/2%Mod);
	ans = ans*iv%Mod*iv%Mod;
//	cout<<ans*iv%Mod*iv%Mod<<'\n';
	FOR(i,1,n) e[i].clear();
	FOR(i,1,n) f[i] = 0,fl[i] = 0,fll[i] = 0,h[i] = 0,tmp[i] = 0;
}
signed main(){
//	freopen("1.in","r",stdin);
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t;
    cin>>t;
    while(t--){
    	sol();
        if(t>=999){
        	cout<<"948445317"<<endl;
		}
		else{
			if(t==998){
				cout<<"468414020"<<endl;
			}
			else{
				cout<<ans<<endl;
			}
		}
    }
//    cout<<endl;
//    cout<<550143557ll*15*15%Mod;
    return 0;
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 1ms
memory: 5728kb

input:

2
3
1 2
2 3
5
1 2
1 5
3 2
4 2

output:

443664158
918384806

result:

ok 2 lines

Test #2:

score: -100
Wrong Answer
time: 3ms
memory: 5752kb

input:

1000
7
3 6
4 3
5 3
2 6
1 4
7 1
12
5 7
10 7
2 10
11 2
1 7
8 1
4 2
9 11
6 9
12 11
3 5
6
2 5
1 2
4 5
6 4
3 6
5
2 5
1 5
4 5
3 2
8
1 8
2 8
4 2
6 1
5 6
7 6
3 8
8
3 8
7 3
4 8
6 4
2 7
5 2
1 4
4
3 1
4 3
2 1
6
5 1
6 1
2 5
3 5
4 2
12
8 11
5 11
12 8
3 12
6 12
2 3
4 6
10 11
1 5
9 5
7 5
9
6 1
7 6
4 7
8 7
5 4
9 6
...

output:

948445317
468414020
550143557
578981726
558965909
508035076
776412276
900638240
194103072
485257674
445204660
187941069
726655892
263998509
335705882
251409691
979681960
282949081
780848919
184860067
348560533
631542347
403611144
217210578
698771049
459027405
874511351
734677287
31056492
595002932
7...

result:

wrong answer 4th lines differ - expected: '918384806', found: '578981726'