#include "dna.h"
#include <bits/stdc++.h>
using namespace std;
map<char, int> mp;
string a, b;
void init(std::string _a, std::string _b) {
a = _a;
b = _b;
mp['A'] = 0;
mp['T'] = 1;
mp['C'] = 2;
}
// 1, 2, 4
// 8, 16, 32
int get_distance(int x, int y) {
vector<vector<int>> d1(3), d2(3);
vector<int> cnt(60);
vector<int> bal(3);
int res = 0;
int left = y - x + 1;
for (int i = x; i <= y; ++i) {
int ai = mp[a[i]];
int bi = mp[b[i]];
if (ai == bi) {
left -= 1;
continue;
}
d1[mp[a[i]]].push_back(i);
d2[mp[b[i]]].push_back(i);
cnt[(1 << ai) + (1 << (bi + 3))] += 1;
bal[ai] += 1;
bal[bi] -= 1;
}
for (int mask1 : {1, 2, 4}) {
for (int mask2 : {8, 16, 32}) {
int rev1 = (1 << (mask1 + 3));
int rev2 = mask2 >> 3;
int take = min(cnt[mask1 + mask2], cnt[rev1 + rev2]);
res += take;
cnt[mask1 + mask2] -= take;
cnt[rev1 + rev2] -= take;
left -= take;
}
}
for (auto& i : bal) {
if (i != 0) return -1;
}
// cerr << "[" << a.substr(x, y - x + 1) << " , " << b.substr(x, y - x + 1) << "] = " << res << "\n";
// assert(res % 2 == 0);
return res + (left / 3) * 2;
}
