#include<bits/stdc++.h>
#include "dna.h"
using namespace std;
int dif[100000], A_T[100000], a_A[100000], b_A[100000], a_T[100000], b_T[100000];
bool check(int x, int y){
int numA_a = a_A[y], numA_b = b_A[y], numT_a = a_T[y], numT_b = b_T[y];
if (x > 0){
numA_a -= a_A[x - 1];
numA_b -= b_A[x - 1];
numT_a -= a_T[x - 1];
numT_b -= b_T[x - 1];
}
return ((numA_a == numA_b) && (numT_a == numT_b));
}
int get_distance(int x, int y){
if (!check(x, y)) return -1;
int res = dif[y] - A_T[y];
if (x > 0) res -= (dif[x - 1] - A_T[x - 1]);
return res;
}
void init(string a, string b){
int n = a.size();
for (int i = 0; i < n; ++i){
if (a[i] != b[i] && a[i] != 'C') dif[i]++;
if (i > 0) dif[i] += dif[i - 1];
if (a[i] == 'A' && b[i] == 'T') A_T[i]++;
if (i > 0) A_T[i] += A_T[i - 1];
if (a[i] == 'A') a_A[i]++;
if (i > 0) a_A[i] += a_A[i - 1];
if (a[i] == 'T') a_T[i]++;
if (i > 0) a_T[i] += a_T[i - 1];
if (b[i] == 'A') b_A[i]++;
if (i > 0) b_A[i] += b_A[i - 1];
if (b[i] == 'T') b_T[i]++;
if (i > 0) b_T[i] += b_T[i - 1];
}
return;
}
