QOJ.ac
QOJ
| 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 |
|---|---|---|---|---|---|---|---|---|---|
| #20442 | #2573. Two Permutations | Appleblue17# | AC ✓ | 1031ms | 24512kb | C++17 | 792b | 2022-02-16 10:02:41 | 2022-05-03 09:55:27 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
const long long N=110,mod=1e9+7,inv2=(mod+1)/2;
long long n,m;
long long dp[2][N][N*N],id;
void gmod(long long &x){
x%=mod;
}
int main(){
cin>>n>>m;
dp[0][0][0]=1;
for(long long i=1;i<=n;i++){
id^=1;
memset(dp[id],0,sizeof(dp[id]));
for(long long j=0;j<=n;j++){
for(long long k=0;k<=m;k++){
long long s=i-1-j,emp=n-(2*s+j);
if(emp>0 && j+1<=n && k+i<=m) gmod(dp[id][j+1][k+i]+=dp[id^1][j][k]*emp%mod);
if(emp>0) gmod(dp[id][j][k]+=dp[id^1][j][k]*emp%mod*(emp-1)%mod);
if(s>0 && j+2<=n && k+2*i<=m) gmod(dp[id][j+2][k+2*i]+=dp[id^1][j][k]*s%mod*s%mod);
if(s>0 && emp>0 && j+1<=n && k+i<=m) gmod(dp[id][j+1][k+i]+=dp[id^1][j][k]*s%mod*emp%mod*2%mod);
}
}
}
cout<<dp[id][n][m];
}
详细
Test #1:
score: 100
Accepted
time: 5ms
memory: 24248kb
input:
2 4
output:
2
result:
ok 1 number(s): "2"
Test #2:
score: 0
Accepted
time: 5ms
memory: 24360kb
input:
3 7
output:
12
result:
ok 1 number(s): "12"
Test #3:
score: 0
Accepted
time: 9ms
memory: 24336kb
input:
4 10
output:
24
result:
ok 1 number(s): "24"
Test #4:
score: 0
Accepted
time: 9ms
memory: 24460kb
input:
4 14
output:
96
result:
ok 1 number(s): "96"
Test #5:
score: 0
Accepted
time: 8ms
memory: 24368kb
input:
5 10
output:
0
result:
ok 1 number(s): "0"
Test #6:
score: 0
Accepted
time: 9ms
memory: 24392kb
input:
5 15
output:
120
result:
ok 1 number(s): "120"
Test #7:
score: 0
Accepted
time: 10ms
memory: 24392kb
input:
5 21
output:
2400
result:
ok 1 number(s): "2400"
Test #8:
score: 0
Accepted
time: 5ms
memory: 24460kb
input:
6 21
output:
720
result:
ok 1 number(s): "720"
Test #9:
score: 0
Accepted
time: 13ms
memory: 24352kb
input:
6 30
output:
25920
result:
ok 1 number(s): "25920"
Test #10:
score: 0
Accepted
time: 10ms
memory: 24388kb
input:
6 27
output:
106560
result:
ok 1 number(s): "106560"
Test #11:
score: 0
Accepted
time: 25ms
memory: 24364kb
input:
20 300
output:
644873710
result:
ok 1 number(s): "644873710"
Test #12:
score: 0
Accepted
time: 28ms
memory: 24360kb
input:
20 139
output:
0
result:
ok 1 number(s): "0"
Test #13:
score: 0
Accepted
time: 51ms
memory: 24364kb
input:
30 470
output:
491424690
result:
ok 1 number(s): "491424690"
Test #14:
score: 0
Accepted
time: 55ms
memory: 24444kb
input:
30 500
output:
8436035
result:
ok 1 number(s): "8436035"
Test #15:
score: 0
Accepted
time: 77ms
memory: 24472kb
input:
40 1000
output:
617159088
result:
ok 1 number(s): "617159088"
Test #16:
score: 0
Accepted
time: 70ms
memory: 24384kb
input:
40 900
output:
729805907
result:
ok 1 number(s): "729805907"
Test #17:
score: 0
Accepted
time: 148ms
memory: 24380kb
input:
60 1830
output:
16340084
result:
ok 1 number(s): "16340084"
Test #18:
score: 0
Accepted
time: 156ms
memory: 24512kb
input:
60 2000
output:
832198921
result:
ok 1 number(s): "832198921"
Test #19:
score: 0
Accepted
time: 607ms
memory: 24472kb
input:
100 5050
output:
437918130
result:
ok 1 number(s): "437918130"
Test #20:
score: 0
Accepted
time: 224ms
memory: 24380kb
input:
100 700
output:
0
result:
ok 1 number(s): "0"
Test #21:
score: 0
Accepted
time: 1031ms
memory: 24376kb
input:
100 10000
output:
0
result:
ok 1 number(s): "0"