ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#214260 | #2763. 幻想乡的拜访 | stawalr | 100 | 1211ms | 59484kb | C++ | 799b | 2024-11-16 20:56:38 | 2024-11-16 23:13:09 |
answer
#include<cstdio>
#define int long long
using namespace std;
const int mn=1e6+5,mod=1e9+7;
int n,ans;
int hd[mn],to[mn<<1],nxt[mn<<1],cnt=1;
int f[mn],sz[mn];
void add(int x,int y)
{
nxt[cnt]=hd[x];
to[cnt]=y;
hd[x]=cnt++;
}
void dfs(int x,int y)
{
sz[x]=x;
f[x]=0;
for(int i=hd[x];i;i=nxt[i])
{
int u=to[i];
if(u==y)continue;
dfs(u,x);
ans+=sz[x]*sz[u]%mod+sz[x]*f[u]%mod+sz[u]*f[x]%mod;
ans%=mod;
sz[x]+=sz[u];
sz[x]%=mod;
f[x]+=f[u]+sz[u];
f[x]%=mod;
}
}
signed main()
{
int x,y;
scanf("%lld",&n);
for(int i=1;i<n;i++)
{
scanf("%lld%lld",&x,&y);
add(x,y);
add(y,x);
}
dfs(1,0);
printf("%lld",ans);
}
详细
小提示:点击横条可展开更详细的信息
Test #1:
score: 10
Accepted
time: 0ms
memory: 544kb
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: 544kb
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: 544kb
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: 704kb
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: 700kb
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: 0ms
memory: 700kb
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: 317ms
memory: 59468kb
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: 292ms
memory: 59356kb
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: 293ms
memory: 59484kb
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: 309ms
memory: 59452kb
input:
1000000 900864 972452 986047 900864 953966 972452 977801 986047 997024 972452 954755 953966 999240 9...
output:
201471911
result:
ok single line: '201471911'