Submission #139704

#	Time	Username	Problem	Language	Result	Execution time	Memory
139704		mlyean00	Growing Vegetable is Fun 3 (JOI19_ho_t3)	C++17	0 / 100	1058 ms	424 KiB

joi2019_ho_t3

#include <bits/stdc++.h>
#ifdef DEBUG
#include "debug.hpp"
#else
#pragma GCC optimize("Ofast")
#define trace(...)
#include <bits/stdc++.h>
#define endl '\n'
#endif

using namespace std;

const string COL = "RGY";

int count_swaps(string const& s, string const& t) {
    int n = s.length();
    vector<stack<int>> st(3);

    int diff = 0;
    for (int i = n - 1; i >= 0; --i) {
        st[COL.find(t[i])].push(i);
    }
    for (int i = 0; i < n; ++i) {
        int c = COL.find(s[i]);
        if (st[c].empty()) return INT_MAX;
        diff += abs(st[c].top() - i);
        st[c].pop();
    }

    assert(diff % 2 == 0);
    for (int i = 0; i < 3; ++i) {
        assert(st[i].empty());
    }

    return diff / 2;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    string s;
    cin >> n >> s;

    int ans = INT_MAX;

    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 1 << (n - 1); ++j) {
            string t;
            int prev_c = i;
            t.push_back(COL[prev_c]);
            for (int k = 0; k < n - 1; ++k) {
                int bit = (j >> k) & 1;
                prev_c = (prev_c + bit + 1) % 3;
                t.push_back(COL[prev_c]);
            }
            ans = min(count_swaps(s, t), ans);
        }
    }

    if (ans == INT_MAX) ans = -1;

    cout << ans << endl;

    return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 55
• Subtask 3: 0 / 15
• Subtask 4: 0 / 25