#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
string as, bs;
vector<int> cc[9];
char letters[3] = {'A', 'T', 'C'};
void init(string a, string b) {
as = a;
bs = b;
int n = a.length();
for (int i = 0; i < 9; ++i) {
cc[i].resize(n + 2, 0);
}
for (int i = 1; i <= n; ++i) {
for (int cx = 0; cx < 3; ++cx) {
for (int cy = 0; cy < 3; ++cy) {
cc[cy * 3 + cx][i] =
cc[cy * 3 + cx][i - 1] +
(as[i - 1] == letters[cx] && bs[i - 1] == letters[cy]);
// printf("cc[%d][%d] = %c %c\n", cx, cy, letters[cx], letters[cy]);
}
}
}
}
int get_distance(int x, int y) {
y++;
/*
cc[0][0] = A A 0
cc[1][1] = T T 4
cc[2][2] = C C 8
cc[0][1] = A T 1
cc[1][0] = T A 3
cc[0][2] = A C 2
cc[2][0] = C A 6
cc[1][2] = T C 5
cc[2][1] = C T 7
*/
int ccs[9];
for (int i = 0; i < 9; ++i)
ccs[i] = cc[i][y] - cc[i][x];
if (ccs[1] + ccs[2] != ccs[3] + ccs[6] ||
ccs[3] + ccs[5] != ccs[1] + ccs[7] || ccs[6] + ccs[7] != ccs[2] + ccs[5])
return -1;
int count = 0;
int remaining = ccs[1] + ccs[2] + ccs[3] + ccs[5] + ccs[6] + ccs[7];
int r1 = min(ccs[1], ccs[3]);
remaining -= r1 * 2;
count += r1;
int r2 = min(ccs[2], ccs[6]);
remaining -= r2 * 2;
count += r2;
int r3 = min(ccs[5], ccs[7]);
remaining -= r3 * 2;
count += r3;
if (remaining)
count += (remaining / 3) * 2;
return count;
}
