Codeforces Round 821 (Div. 2) D2. Zero-One

题目

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define fi first
#define se second
#define lson p << 1
#define rson p << 1 | 1
const int maxn = 1e5 + 5, inf = 1e18, maxm = 4e4 + 5;
const int N = 1e6;
 const int mod = 1e9 + 7;
// const int mod = 998244353;
//const __int128 mod = 212370440130137957LL;
// int a[505][5005];
// bool vis[505][505];
int n, m;
int a[maxn];

string s;

struct Node{
    // int val, id;
    // bool operator<(const Node &u)const{
    //     return val < u.val;//!!!!!!!!!!!!!!!!!!
    // }
    int v, w;
};

int f[5005][5005];
//long long ? maxn ? n? m?
void solve(){
    int res = 0;
    cin >> n;
    int x, y;
    cin >> x >> y;
    char ch;
    for(int i = 1; i <= n; i++){
        cin >> ch;
        a[i] = ch - '0';
    }
    vector<int> pos;
    pos.pb(0);
    for(int i = 1; i <= n; i++){
        cin >> ch;
        a[i] ^= ch - '0';
        if(a[i]){
            pos.pb(i);
        }
    }
    int m = pos.size() - 1;
    if(m % 2 == 1){
        cout << -1 << '\n';
        return;
    }
    if(x >= y){
        if(m == 2){
            if(pos[1] == pos[2] - 1){
                cout << min(x, 2LL * y) << '\n';
            }
            else{
                cout << y << '\n';
            }
        }
        else{
            cout << m / 2 * y << '\n';
        }
        return;
    }
    for(int i = 0; i <= m + 1; i++){
        for(int j = 0; j <= m + 1; j++){
            if(i < j)
                f[i][j] = inf;
            else f[i][j] = 0;
        }
    }
    f[0][0] = 0;
    for(int len = 2; len <= m; len += 2){
        for(int i = 1; i + len - 1 <= m; i++){
            int j = i + len - 1;
            f[i][j] = min({f[i + 2][j] + min((pos[i + 1] - pos[i]) * x, y),
                          f[i][j - 2] + min((pos[j] - pos[j - 1]) * x, y), 
                          f[i + 1][j - 1] + min((pos[j] - pos[i]) * x, y)});
        }
    }
    cout << f[1][m] << '\n';
}   
    
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);

    int T = 1;
    cin >> T;
    while (T--)
    {
        solve();
    }
    return 0;
}