Longest Substring of given characters by replacing at most K characters for Q queries

#include <bits/stdc++.h>

using namespace std;

int dp[1001][1001][26];

int ans[1001][26];

void preprocess(string s)

{

    int n = s.length();

    memset(dp, 0, sizeof(dp));

    for (int i = 1; i <= n; i++) {

        dp[i][0][s[i - 1] - 'a'] = 1;

    }

    for (int i = 1; i <= n; i++) {

        for (int j = 0; j <= i; j++) {

            for (int k = 0; k < 26; k++) {

                if (s[i - 1] == char(k + 'a'))

                    dp[i][j][k] = dp[i - 1][j][k] + 1;

                else if (j != 0)

                    dp[i][j][k] = dp[i - 1][j - 1][k] + 1;

            }

        }

    }

    memset(ans, 0, sizeof(ans));

    for (int i = 1; i <= n; i++) {

        for (int j = 0; j < 26; j++) {

            for (int k = 1; k <= n; k++)

                ans[i][j] = max(ans[i][j], dp[k][i][j]);

        }

    }

}

vector<int> query(string s,

                  vector<pair<int, char> >& queries)

{

    preprocess(s);

    vector<int> res;

    for (auto u : queries) {

        res.push_back(ans[u.first][u.second - 'a']);

    }

    return res;

}

int main()

{

    string s = "yamatonadeshiko";

    vector<pair<int, char> > queries;

    queries.push_back({ 1, 'a' });

    queries.push_back({ 2, 'a' });

    queries.push_back({ 3, 'a' });

    queries.push_back({ 4, 'a' });

    queries.push_back({ 5, 'a' });

    queries.push_back({ 1, 'b' });

    queries.push_back({ 2, 'b' });

    queries.push_back({ 3, 'b' });

    queries.push_back({ 4, 'b' });

    queries.push_back({ 5, 'b' });

    vector<int> sol = query(s, queries);

    for (int x : sol)

        cout << x << " ";

    return 0;

}