# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
143358 | nicolaalexandra | Mate (COCI18_mate) | C++14 | 2065 ms | 26312 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <iostream>
#include <vector>
#include <set>
#include <cstring>
#define DIM 2010
#define MOD 1000000007
using namespace std;
//ifstream cin ("date.in");
//ofstream cout ("date.out");
int v[DIM],c[DIM][DIM],f[DIM],dp[DIM][30][30],a[DIM][30];
char s[DIM],l1,l2;
int n,i,j,x,y,q,lg;
int main (){
cin>>s+1;
n = strlen(s+1);
for (i=1;i<=n;i++)
v[i] = s[i] - 'a' + 1;
c[0][0] = c[1][0] = c[1][1] = 1;
for (i=2;i<=n;i++){
c[i][0] = 1;
for (j=1;j<=i;j++)
c[i][j] = (c[i-1][j] + c[i-1][j-1])%MOD;
}
/// a[i][x] - in cate moduri pot selecta s[i],j (am nevoie sa stiu pozitia primului)
for (i=1;i<=n;i++)
for (j=i+1;j<=n;j++)
a[i][v[j]]++;
/// dp[i][x][y] - cate siruri de lungime i care se termina cu xy pot obtine
for (lg=2;lg<=n;lg++){
for (i=lg-1;i<=n;i++){
x = v[i];
for (y=1;y<=26;y++)
dp[lg][x][y] = (dp[lg][x][y]+1LL*a[i][y]*c[i-1][lg-2]%MOD)%MOD;
}}
cin>>q;
for (;q--;){
cin>>lg>>l1>>l2;
x = l1-'a'+1, y = l2-'a'+1;
cout<<dp[lg][x][y]<<"\n";
}
return 0;
}
Compilation message (stderr)
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