Word Worries

input/code.cpp: In function 'int comp(std::__cxx11::string, std::__cxx11::string)':
input/code.cpp:13:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int j = 0; j < a.length(); ++j) {
                 ~~^~~~~~~~~~~~

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;


const int N = 1e5 + 5;

vector<string> v;

int comp(string a, string b) {
	for(int j = 0; j < a.length(); ++j) {
		int k = (int) a[j];
		int n = (int) b[j];
		if(k < n) {
			return 1;
		} else if (k > n) {
			return -1;
		}
	}
	return 0;
}

int main() {

	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= n; ++i) {
		string s;
		cin >> s;
		v.push_back(s);
	}
	sort(v.begin(), v.end());

	int ans = 0;
	int k = 0;
	for(int i = 0; i < n; ++i) {
		if(v[i] == v[0]) {
			++ans;
			k = i;
		} else {
			break;
		}
	}

	string a = v[0];

	for(int j = 0; j < m; ++j) {
		if(a[j] != 'z') {
			a[j] = 'z';
			break;
		}
	}


	for(int i = k + 1; i < n; ++i) {
		//Check if v[i] can be first
		if(k == 0) {
			if(comp(a, v[i]) != 1) {
				if(comp(v[i], v[k+1]) == 0) {
					++ans;
					continue;
				}
			}
		}

		string b = v[i];
		for(int j = 0; j < m; ++j) {
			if(b[j] != 'a') {
				b[j] = 'a';
				break;
			}
		}


		if(comp(b, v[0]) != -1) {
			++ans;
		}
	}

	cout << ans << "\n";

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED