CUBE-T085: String Partition

#include <bits/stdc++.h>
using namespace std;

string str;
int len;

int diffChar(int sz){
    int cnt = 0;
    for(int i = 0; i < sz; ++i){
        int charCnt[27] = {};
        int mx = 0;
        for(int j = i; j < len; j += sz){
            ++charCnt[str[j] - 'a'];
            mx = max(mx, charCnt[str[j] - 'a']);
        }
        cnt += len / sz - mx;
    }
    return cnt;
}

int main(){

    cin >> str;
    len = str.size();
    int upBound = sqrt(len);
    int mn = len;
    for(int i = 1; i <= upBound; ++i){
        if(len % i == 0){
            mn = min(mn, diffChar(i));
            if(i != 1 && i != len / i){
                mn = min(mn, diffChar(len / i));
            }
        }
    }
    cout << mn;

    return 0;
}