Submission #139728

#	Time	Username	Problem	Language	Result	Execution time	Memory
139728		mlyean00	Growing Vegetable is Fun 3 (JOI19_ho_t3)	C++14	20 / 100	20 ms	552 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 s, string const& t) {
    int n = s.length();
    int ans = 0;
    for (int i = 0; i < n; ++i) {
        int j;
        for (j = i; j < n; ++j) {
            if (s[j] == t[i]) break;
        }
        if (j == n) return INT_MAX;
        for (; j > i; --j) {
            ++ans;
            swap(s[j], s[j - 1]);
        }
    }
    return ans;
}

int subtask_1(int n, string 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;

    return ans;
}

int subtask_3(int n, string s) {
    string t1, t2;
    for (int i = 0; i < n; ++i) {
        t1.push_back("RG"[i % 2]);
        t2.push_back("GR"[i % 2]);
    }
    int ans = min(count_swaps(s, t1), count_swaps(s, t2));

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

    return ans;
}

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

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

    int ans;
    if (n <= 15) {
        ans = subtask_1(n, s);
    } else {
        ans = subtask_3(n, s);
    }

    cout << ans << endl;

    return 0;
}

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