#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5+5;
int n;
int qca[MAXN][3], qcb[MAXN][3];
int df[MAXN][3][3];
int id(char c) {
if (c == 'A') return 0;
else if (c == 'T') return 1;
else return 2;
}
void init(string a, string b) {
n = a.size();
a = '.'+a;
b = '.'+b;
qca[0][0] = qca[0][1] = qca[0][2] = qcb[0][0] = qcb[0][1] = qcb[0][2] = 0;
df[0][0][0] = df[0][0][1] = df[0][0][2] = df[0][1][0] = df[0][1][1] = df[0][1][2] = df[0][2][0] = df[0][2][1] = df[0][2][2] = 0;
for (int i = 1; i <= n; i++) {
qca[i][0] = qca[i-1][0];
qca[i][1] = qca[i-1][1];
qca[i][2] = qca[i-1][2];
qcb[i][0] = qcb[i-1][0];
qcb[i][1] = qcb[i-1][1];
qcb[i][2] = qcb[i-1][2];
df[i][0][0] = df[i-1][0][0];
df[i][0][1] = df[i-1][0][1];
df[i][0][2] = df[i-1][0][2];
df[i][1][0] = df[i-1][1][0];
df[i][1][1] = df[i-1][1][1];
df[i][1][2] = df[i-1][1][2];
df[i][2][0] = df[i-1][2][0];
df[i][2][1] = df[i-1][2][1];
df[i][2][2] = df[i-1][2][2];
qca[i][id(a[i])]++;
qcb[i][id(b[i])]++;
df[i][id(a[i])][id(b[i])]++;
}
}
int get_distance(int x, int y) {
x++; y++;
if (qca[y][0] - qca[x-1][0] != qcb[y][0] - qcb[x-1][0]) return -1;
if (qca[y][1] - qca[x-1][1] != qcb[y][1] - qcb[x-1][1]) return -1;
if (qca[y][2] - qca[x-1][2] != qcb[y][2] - qcb[x-1][2]) return -1;
int cdf[3][3];
cdf[0][0] = df[y][0][0] - df[x-1][0][0];
cdf[0][1] = df[y][0][1] - df[x-1][0][1];
cdf[0][2] = df[y][0][2] - df[x-1][0][2];
cdf[1][0] = df[y][1][0] - df[x-1][1][0];
cdf[1][1] = df[y][1][1] - df[x-1][1][1];
cdf[1][2] = df[y][1][2] - df[x-1][1][2];
cdf[2][0] = df[y][2][0] - df[x-1][2][0];
cdf[2][1] = df[y][2][1] - df[x-1][2][1];
cdf[2][2] = df[y][2][2] - df[x-1][2][2];
int sum = 0;
for (int i = 0; i <= 2; i++)
for (int j = 0; j <= 2; j++)
if (i != j) sum += cdf[i][j];
return (sum+1)/2;
}
