NOI.AC
| ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
|---|---|---|---|---|---|---|---|---|---|
| #214256 | #2763. 幻想乡的拜访 | 142857Harry | 100 | 1012ms | 38224kb | C++11 | 688b | 2024-11-16 20:44:13 | 2024-11-16 23:12:51 |
answer
#include <bits/stdc++.h>
using namespace std;
const int mod=1e9+7;
struct edge{
int v,nxt;
}e[2000005];
long long n,all,ans,pos,u,v;
long long siz[1000005],head[1000005];
void addedge(int u,int v){
e[++pos]={v,head[u]};
head[u]=pos;
}
void dfs(int u,int f){
siz[u]=u;
for(int i=head[u];i;i=e[i].nxt){
int v=e[i].v;
if(v==f)
continue;
dfs(v,u);
siz[u]+=siz[v];
(ans+=(siz[v]%mod)*((all-siz[v])%mod)%mod)%=mod;
}
}
signed main(){
std::ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
cin>>n;
all=n*(n+1)/2;
for(int i=1;i<n;i++){
cin>>u>>v;
addedge(u,v);
addedge(v,u);
}
dfs(1,0);
cout<<ans;
return 0;
}
//Skadi_H
Details
小提示：点击横条可展开更详细的信息
Test #1:
score: 10
Accepted
time: 0ms
memory: 1256kb
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: 0ms
memory: 1256kb
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: 0ms
memory: 1256kb
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: 0ms
memory: 1364kb
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: 0ms
memory: 1368kb
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: 1ms
memory: 1360kb
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: 10
Accepted
time: 247ms
memory: 38200kb
input:
1000000 984750 990109 970095 984750 996126 970095 998081 990109 987074 970095 962711 970095 916630 9...
output:
192557796
result:
ok single line: '192557796'
Test #8:
score: 10
Accepted
time: 266ms
memory: 38044kb
input:
1000000 947305 936749 948062 947305 970449 947305 988744 948062 998703 988744 986194 947305 997762 9...
output:
160385007
result:
ok single line: '160385007'
Test #9:
score: 10
Accepted
time: 242ms
memory: 38224kb
input:
1000000 952012 962256 982471 962256 955412 952012 953636 962256 991390 952012 998704 953636 999294 9...
output:
308556344
result:
ok single line: '308556344'
Test #10:
score: 10
Accepted
time: 256ms
memory: 38180kb
input:
1000000 900864 972452 986047 900864 953966 972452 977801 986047 997024 972452 954755 953966 999240 9...
output:
201471911
result:
ok single line: '201471911'
