QOJ.ac

QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#688335#9530. A Game On TreedoyoWA 1ms3672kbC++202.4kb2024-10-30 04:56:542024-10-30 04:56:55

Judging History

This is the latest submission verdict.

  • [2024-10-30 04:56:55]
  • Judged
  • Verdict: WA
  • Time: 1ms
  • Memory: 3672kb
  • [2024-10-30 04:56:54]
  • 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 
//		意义有问题,h[x] += 的部分不应该乘以后面的,这是算到 ans 里的部分 
//		h[x] += (tmp[nxt] + h[nxt])%Mod * (totsize[x]-sz[nxt])%Mod,h[x] %= Mod;
		ans += (tmp[nxt] + h[nxt])%Mod * (totsize[x]-sz[nxt])%Mod,h[x] %= Mod;
		h[x] += (tmp[nxt] + h[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];
	}
}
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<<918384806ll*100%Mod;
    return 0;
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 1ms
memory: 3604kb

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: 1ms
memory: 3672kb

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
918384806
711758412
487662742
776412276
869581749
159269935
765628773
383584638
887328316
811135414
161332423
760637552
908032643
677183671
282949081
283945063
221832080
433351719
244468006
95511035
771790774
698771049
436917530
413593588
958772958
31056492
592538131
49...

result:

wrong answer 9th lines differ - expected: '240852807', found: '159269935'