Submission #556962

#	Time	Username	Problem	Language	Result	Execution time	Memory
556962		Alexandruabcde	Mutating DNA (IOI21_dna)	C++17	100 / 100	54 ms	8596 KiB

dna

#include "dna.h"
#include <bits/stdc++.h>

using namespace std;

constexpr int NMAX = 1e5 + 5;

int N;
int pref[NMAX][3][3];
int fr[NMAX][3];

int Value (char ch) {
    if (ch == 'A') return 0;
    if (ch == 'C') return 1;
    return 2;
}

void init(std::string a, std::string b) {
    N = a.size();
    for (int i = 1; i <= N; ++ i ) {
        pref[i][Value(a[i-1])][Value(b[i-1])] = 1;

        for (int j = 0; j < 3; ++ j )
            for (int k = 0; k < 3; ++ k )
                pref[i][j][k] += pref[i-1][j][k];

        fr[i][Value(a[i-1])] ++;
        fr[i][Value(b[i-1])] --;

        for (int j = 0; j < 3; ++ j )
            fr[i][j] += fr[i-1][j];
    }
}

int get_distance(int x, int y) {
    int mat[3][3];
    memset(mat, 0, sizeof(mat));
    int freq[3];
    memset(freq, 0, sizeof(freq));

    for (int i = 0; i < 3; ++ i )
        for (int j = 0; j < 3; ++ j )
            mat[i][j] = pref[y+1][i][j] - pref[x][i][j];

    for (int i = 0; i < 3; ++ i )
        freq[i] = fr[y+1][i] - fr[x][i];

    bool ok = 1;
    for (int i = 0; i < 3; ++ i )
        if (freq[i] != 0) ok = 0;

    if (!ok) return -1;

    int ans = 0;
    for (int i = 0; i < 3; ++ i ) {
        for (int j = i+1; j < 3; ++ j ) {
            int value = min(mat[i][j], mat[j][i]);

            ans = ans + value;
            mat[i][j] -= value;
            mat[j][i] -= value;
        }
    }

    int Max = 0;
    for (int i = 0; i < 3; ++ i ) {
        for (int j = 0; j < 3; ++ j ) {
            if (i == j) continue;

            Max = max(Max, mat[i][j]);
        }
    }

    return ans + 2 * Max;
}

• Subtask 1: 21 / 21
• Subtask 2: 22 / 22
• Subtask 3: 13 / 13
• Subtask 4: 28 / 28
• Subtask 5: 16 / 16