Bittijono

input/code.cpp: In function 'void $()':
input/code.cpp:14:8: warning: unused variable 'ans' [-Wunused-variable]
   14 |     ll ans = 0;
      |        ^~~

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

const int mxN = 1e5;
const ll INF = 1e18;
void $() {
    ll n, a, b;
    cin >> n >> a >> b;
    string s, t;
    cin >> s >> t;
    vector<int> x(n);
    for (int i=0; i<n; i++) x[i] = s[i]^t[i];
    ll ans = 0;
    vector<array<ll, 2>> comp;
    int l = 0;
    while (l<n) {
        int r = l;
        while (r<n && x[l] == x[r]) r++;
        comp.push_back({x[l], min(ll(r-l)*a, b)});
        l = r;
    };
    int M = comp.size();
    vector<ll> dp(M);
    ll ext = INF;
    for (int i=0; i<M; i++) {
        if (comp[i][0] == 0) {
            if (i) dp[i] = dp[i-1];
            ext += comp[i][1];
        } else {
            dp[i] = comp[i][1];
            if (i) dp[i] += dp[i-1];
            dp[i] = min(dp[i], ext);
            ll x = b;
            if (i) x+= dp[i-1];
            ext = min(ext, x);
        }; 
    };

    cout << min(ext, dp.back()) << '\n';
}
int main() {
    cin.tie(0)->sync_with_stdio(0);
    $();
}

Test 1 (public)

Group: 1, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 3

Verdict: ACCEPTED

Test 4

Group: 1, 3

Verdict: ACCEPTED

Test 5

Group: 1, 3

Verdict: ACCEPTED

Test 6

Group: 3

Verdict: ACCEPTED

Test 7

Group: 2, 3

Verdict: ACCEPTED

Test 8

Group: 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 2, 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED

Test 16

Group: 1, 2, 3

Verdict: ACCEPTED

Test 17

Group: 1, 3

Verdict: ACCEPTED

Test 18

Group: 1, 3

Verdict: ACCEPTED

Test 19

Group: 3

Verdict: ACCEPTED

Test 20

Group: 3

Verdict: ACCEPTED