#include <bits/stdc++.h>
using namespace std;
const int mod=1e9+7;
const int N=2005;
int add(int x, int y){ x+=y;return x>=mod?x-mod:x;}
void ADD(int &x, int y){ x=add(x,y);}
int sub(int x, int y){ x-=y;return x<0?x+mod:x;}
void SUB(int &x, int y){ x=sub(x,y);}
int dp[N][N][2],sum[N][N][2];
int Get(int i, int l, int r, int t)
{
int x=sum[i][r][t]-sum[i][l-1][t];
if(x<0) x+=mod;
return x;
}
int main()
{
int n,cs,cf;
scanf("%i %i %i",&n,&cs,&cf);
dp[1][1][0]=dp[1][1][1]=1;
for(int l=2;l<=n;l++)
{
for(int i=1;i<=l-1;i++)
for(int j=1;j<=l-1;j++)
{
sum[i][j][0]=sum[i][j-1][0]+dp[i][j][0];
if(sum[i][j][0]>=mod) sum[i][j][0]-=mod;
sum[i][j][1]=sum[i][j-1][1]+dp[i][j][1];
if(sum[i][j][1]>=mod) sum[i][j][1]-=mod;
}
for(int i=1;i<=l;i++)
for(int j=1;j<=l;j++)
{
if(i!=j)
{
dp[i][j][0]=Get(i-(i>j),1,j-1,1);
dp[i][j][1]=Get(i-(i>j),j,l-1,0);
}
else dp[i][j][0]=dp[i][j][1]=0;
}
}
int ans=add(dp[cs][cf][0],dp[cs][cf][1]);
printf("%i\n",ans);
return 0;
}
Compilation message
kangaroo.cpp: In function 'int main()':
kangaroo.cpp:19:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%i %i %i",&n,&cs,&cf);
~~~~~^~~~~~~~~~~~~~~~~~~~~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
376 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
376 KB |
Output is correct |
3 |
Correct |
2 ms |
504 KB |
Output is correct |
4 |
Correct |
2 ms |
632 KB |
Output is correct |
5 |
Correct |
2 ms |
632 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
7 |
Correct |
2 ms |
632 KB |
Output is correct |
8 |
Correct |
2 ms |
636 KB |
Output is correct |
9 |
Correct |
2 ms |
632 KB |
Output is correct |
10 |
Correct |
2 ms |
632 KB |
Output is correct |
11 |
Correct |
2 ms |
632 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
376 KB |
Output is correct |
3 |
Correct |
2 ms |
504 KB |
Output is correct |
4 |
Correct |
2 ms |
632 KB |
Output is correct |
5 |
Correct |
2 ms |
632 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
7 |
Correct |
2 ms |
632 KB |
Output is correct |
8 |
Correct |
2 ms |
636 KB |
Output is correct |
9 |
Correct |
2 ms |
632 KB |
Output is correct |
10 |
Correct |
2 ms |
632 KB |
Output is correct |
11 |
Correct |
2 ms |
632 KB |
Output is correct |
12 |
Correct |
24 ms |
2552 KB |
Output is correct |
13 |
Correct |
21 ms |
2348 KB |
Output is correct |
14 |
Correct |
25 ms |
2552 KB |
Output is correct |
15 |
Correct |
25 ms |
2552 KB |
Output is correct |
16 |
Correct |
24 ms |
2552 KB |
Output is correct |
17 |
Correct |
25 ms |
2552 KB |
Output is correct |
18 |
Correct |
18 ms |
2168 KB |
Output is correct |
19 |
Correct |
24 ms |
2552 KB |
Output is correct |
20 |
Correct |
25 ms |
2552 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
376 KB |
Output is correct |
3 |
Correct |
2 ms |
504 KB |
Output is correct |
4 |
Correct |
2 ms |
632 KB |
Output is correct |
5 |
Correct |
2 ms |
632 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
7 |
Correct |
2 ms |
632 KB |
Output is correct |
8 |
Correct |
2 ms |
636 KB |
Output is correct |
9 |
Correct |
2 ms |
632 KB |
Output is correct |
10 |
Correct |
2 ms |
632 KB |
Output is correct |
11 |
Correct |
2 ms |
632 KB |
Output is correct |
12 |
Correct |
24 ms |
2552 KB |
Output is correct |
13 |
Correct |
21 ms |
2348 KB |
Output is correct |
14 |
Correct |
25 ms |
2552 KB |
Output is correct |
15 |
Correct |
25 ms |
2552 KB |
Output is correct |
16 |
Correct |
24 ms |
2552 KB |
Output is correct |
17 |
Correct |
25 ms |
2552 KB |
Output is correct |
18 |
Correct |
18 ms |
2168 KB |
Output is correct |
19 |
Correct |
24 ms |
2552 KB |
Output is correct |
20 |
Correct |
25 ms |
2552 KB |
Output is correct |
21 |
Correct |
738 ms |
12420 KB |
Output is correct |
22 |
Correct |
893 ms |
13764 KB |
Output is correct |
23 |
Correct |
1132 ms |
15480 KB |
Output is correct |
24 |
Execution timed out |
2048 ms |
21116 KB |
Time limit exceeded |
25 |
Halted |
0 ms |
0 KB |
- |