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#155662#6410. Classical DP ProblemForever_Young#WA 18ms105408kbC++141.7kb2023-09-01 23:51:242023-09-01 23:51:25

Judging History

你现在查看的是最新测评结果

  • [2023-09-01 23:51:25]
  • 评测
  • 测评结果:WA
  • 用时:18ms
  • 内存:105408kb
  • [2023-09-01 23:51:24]
  • 提交

answer

#include<bits/stdc++.h>
using namespace std;
int n,a[5050],r,dp[5050][5050],res,fac[5050],ifac[5050],g[5050][5050];
const int mo=998244353;

int ksm(int x,int y){
	int res=1;
	while (y){
		if (y&1) res=1ll*res*x%mo;
		x=1ll*x*x%mo;
		y/=2;
	}
	return res;
}

int c(int x,int y){//x>=y
	if (x<y) return 0;
	return 1ll*fac[x]*ifac[y]%mo*ifac[x-y]%mo;
}

int main(){
	//freopen("D.in","r",stdin);
	scanf("%d",&n);
	for (int i=1;i<=n;i++)
		scanf("%d",&a[i]);
	for (int i=n;i;i--){
		if (r>=a[i]) break;
		r++;
	}
	
	dp[n][a[n-r]]=1;
	for (int i=n;i>n-r;i--)
		for (int j=0;j<=a[n-r];j++){
			//printf("%d %d %d\n",i,j,dp[0][i][j]);
			dp[i-1][j]=(dp[i-1][j]+1ll*dp[i][j]*(a[i]-j))%mo;
			if (j)
				dp[i-1][j-1]=(dp[i-1][j-1]+1ll*dp[i][j]*j)%mo;
	}
	res=dp[n-r][0];
	memset(dp,0,sizeof(dp));
	//printf("%d\n",res);
	
	dp[n][a[n-r+1]]=1;
	for (int i=n;i>n-r;i--)
		for (int j=0;j<=a[n-r+1];j++){
			//printf("%d %d %d\n",i,j,dp[0][i][j]);
			dp[i-1][j]=(dp[i-1][j]+1ll*dp[i][j]*(a[i]-j))%mo;
			if (j)
				dp[i-1][j-1]=(dp[i-1][j-1]+1ll*dp[i][j]*j)%mo;
	}
	res=(res-dp[n-r][0]+mo)%mo;
	memset(dp,0,sizeof(dp));
	//printf("%d\n",res);
	
	fac[0]=1;
	for (int i=1;i<=n;i++) fac[i]=1ll*fac[i-1]*i%mo;
	ifac[n]=ksm(fac[n],mo-2);
	for (int i=n;i;i--) ifac[i-1]=1ll*ifac[i]*i%mo;
	g[1][0]=1;
	for (int i=1;i<=n;i++){
		//0
		//for (int j=0;j<=r;j++) 
			//printf("%d %d %d\n",i,j,g[i][j]);
		if (a[i]<=r){
			for (int j=0;j<=r;j++) g[i+1][j]=(g[i+1][j]+g[i][j])%mo;
		}
		//1
		for (int j=0;j<r;j++){
			if (g[i][j]==0) continue;
			for (int k=j+1;k<=r&&k<=a[i];k++){
				g[i+1][k]=(g[i+1][k]+1ll*g[i][j]*c(min(a[i],r)-j,k-j))%mo;
			}
		}
	}
	//printf("%d\n",g[n+1][r]);
	res=(res+g[n+1][r])%mo;
	printf("%d %d\n",r,res);
}

详细

Test #1:

score: 100
Accepted
time: 18ms
memory: 105192kb

input:

3
1 2 3

output:

2 6

result:

ok 2 number(s): "2 6"

Test #2:

score: 0
Accepted
time: 8ms
memory: 103884kb

input:

1
1

output:

1 1

result:

ok 2 number(s): "1 1"

Test #3:

score: 0
Accepted
time: 18ms
memory: 104432kb

input:

2
1 1

output:

1 2

result:

ok 2 number(s): "1 2"

Test #4:

score: 0
Accepted
time: 7ms
memory: 104536kb

input:

2
2 2

output:

2 6

result:

ok 2 number(s): "2 6"

Test #5:

score: 0
Accepted
time: 7ms
memory: 104440kb

input:

3
1 1 1

output:

1 3

result:

ok 2 number(s): "1 3"

Test #6:

score: 0
Accepted
time: 12ms
memory: 105408kb

input:

3
2 2 2

output:

2 9

result:

ok 2 number(s): "2 9"

Test #7:

score: 0
Accepted
time: 8ms
memory: 104916kb

input:

3
3 3 3

output:

3 48

result:

ok 2 number(s): "3 48"

Test #8:

score: 0
Accepted
time: 12ms
memory: 103684kb

input:

5
1 1 3 3 4

output:

3 47

result:

ok 2 number(s): "3 47"

Test #9:

score: 0
Accepted
time: 12ms
memory: 103632kb

input:

10
2 4 5 5 5 5 6 8 8 10

output:

5 864

result:

ok 2 number(s): "5 864"

Test #10:

score: -100
Wrong Answer
time: 12ms
memory: 104708kb

input:

30
6 8 9 9 9 10 13 14 15 15 16 17 17 18 20 22 22 23 23 24 24 25 25 25 27 28 28 29 29 30

output:

17 974135375

result:

wrong answer 2nd numbers differ - expected: '986189864', found: '974135375'