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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#214231#2763. 幻想乡的拜访White_Wat602518ms67260kbC++11557b2024-11-16 18:42:392024-11-16 23:10:33

answer

#include<bits/stdc++.h>

using namespace std;

const int N = 1000010, mod = 1e9+7;

typedef long long ll;
int n;
vector<int> g[N];
int s[N];
ll S,ans;

void dfs(int u,int fa){
	s[u]=u;
	for(auto v:g[u]){
		if(v==fa) continue;
		dfs(v,u);
		s[u]+=s[v];
		(ans+=(1ll*s[v]*((S-s[v]+mod)%mod)))%=mod;
	}
}

int main(){
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	
	cin>>n;
	S=1ll*(1+n)*(n)/2;
	for(int i=1;i<n;i++){
		int u,v;cin>>u>>v;
		g[u].push_back(v),g[v].push_back(u);
	}
	dfs(1,1);
	cout<<ans;
	
	return 0;
}

Details

小提示:点击横条可展开更详细的信息

Test #1:

score: 10
Accepted
time: 4ms
memory: 24704kb

input:

200
20 160
90 160
5 90
78 90
186 90
149 90
104 78
136 160
106 78
100 106
168 90
30 5
85 136
28 149
1...

output:

104425891

result:

ok single line: '104425891'

Test #2:

score: 10
Accepted
time: 10ms
memory: 24704kb

input:

200
49 91
20 91
147 91
131 20
36 131
9 131
51 147
173 51
32 36
169 51
180 51
2 91
133 2
72 20
14 169...

output:

145567217

result:

ok single line: '145567217'

Test #3:

score: 10
Accepted
time: 7ms
memory: 24704kb

input:

200
44 72
187 72
115 72
124 115
80 124
34 72
22 115
162 34
123 44
93 22
135 80
5 124
112 72
76 187
3...

output:

226420652

result:

ok single line: '226420652'

Test #4:

score: 10
Accepted
time: 8ms
memory: 24828kb

input:

3000
940 1649
220 1649
1438 1649
2264 1649
1467 940
1825 220
1646 940
571 220
1419 220
2509 1438
264...

output:

781596579

result:

ok single line: '781596579'

Test #5:

score: 10
Accepted
time: 8ms
memory: 24824kb

input:

3000
2156 216
2422 2156
2801 216
2504 2156
2701 2156
2582 2801
1558 2156
864 2582
737 864
2919 1558
...

output:

236427659

result:

ok single line: '236427659'

Test #6:

score: 10
Accepted
time: 3ms
memory: 24820kb

input:

3000
2966 2885
2657 2885
2613 2966
1686 2613
2803 2885
191 2657
2824 2657
675 2657
2693 191
2798 191...

output:

688220644

result:

ok single line: '688220644'

Test #7:

score: 0
Wrong Answer
time: 451ms
memory: 67236kb

input:

1000000
984750 990109
970095 984750
996126 970095
998081 990109
987074 970095
962711 970095
916630 9...

output:

586845217

result:

wrong answer 1st lines differ - expected: '192557796', found: '586845217'

Test #8:

score: 0
Wrong Answer
time: 469ms
memory: 67040kb

input:

1000000
947305 936749
948062 947305
970449 947305
988744 948062
998703 988744
986194 947305
997762 9...

output:

957239069

result:

wrong answer 1st lines differ - expected: '160385007', found: '957239069'

Test #9:

score: 0
Wrong Answer
time: 726ms
memory: 67260kb

input:

1000000
952012 962256
982471 962256
955412 952012
953636 962256
991390 952012
998704 953636
999294 9...

output:

595086148

result:

wrong answer 1st lines differ - expected: '308556344', found: '595086148'

Test #10:

score: 0
Wrong Answer
time: 832ms
memory: 67208kb

input:

1000000
900864 972452
986047 900864
953966 972452
977801 986047
997024 972452
954755 953966
999240 9...

output:

480833153

result:

wrong answer 1st lines differ - expected: '201471911', found: '480833153'