Submission #257758

#	Time	Username	Problem	Language	Result	Execution time	Memory
257758		updown1	Mate (COCI18_mate)	C++17	80 / 100	2072 ms	29592 KiB

mate

/*
Code by @marlov
*/
#include <bits/stdc++.h>
using namespace std;

#define maxV 2005
#define MOD 1000000007

string s;
int Q;
long long pc[maxV][maxV];
long long dp[maxV][26];

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	cin>>s;
	cin>>Q;
	//precomute pc[n][m] which is the nCm
	for(int i=0;i<maxV;i++){
		pc[i][0]=1;
		for(int j=1;j<i;j++){
			pc[i][j]=pc[i-1][j]+pc[i-1][j-1];
			pc[i][j]%=MOD;
		}
		pc[i][i]=1;
	}
	for(int i=0;i<26;i++){
		for(int j=s.length()-1;j>=0;j--){
			if(s[j]=='a'+i){
				dp[j][i]++;
			}
			if(j<s.length()-1){
				dp[j][i]+=dp[j+1][i];
			}
		}
	}
	long long tl;
	char fc,sc;
	for(int i=0;i<Q;i++){
		long long result=0;
		cin>>tl>>fc>>sc;
		for(int j=tl-2;j<s.length()-1;j++){
			if(s[j]==fc){
				result= (result + pc[j][tl-2]*(dp[j+1][sc-'a']))%MOD;
			}
		}
		cout<<result<<'\n';
	}
    return 0;
}

Compilation message (stderr)

mate.cpp: In function 'int main()':
mate.cpp:33:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(j<s.length()-1){
       ~^~~~~~~~~~~~~
mate.cpp:43:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=tl-2;j<s.length()-1;j++){
                  ~^~~~~~~~~~~~~

• Subtask 1: 80 / 100