Submission #852862

#	Time	Username	Problem	Language	Result	Execution time	Memory
852862		ntkphong	Mutating DNA (IOI21_dna)	C++17	100 / 100	76 ms	20480 KiB

dna

#include "dna.h"
#include <bits/stdc++.h>
using namespace std;

const char ch[] = {'A', 'T', 'C'};

int n, m, k;
string ADN[6];
vector<vector<int>> prefix; 
vector<vector<int>> sumA, sumB;


void init(string a, string b) { 
    n = a.size();
    m = 6; k = 3;
    
    ADN[0] = "AT";
    ADN[1] = "AC";
    ADN[2] = "TC";
    ADN[3] = "CT";
    ADN[4] = "CA";
    ADN[5] = "TA";
        
    prefix.resize(n, vector<int> (m, 0));
    sumA.resize(n, vector<int> (k, 0));
    sumB.resize(n, vector<int> (k, 0));
    
    for(int i = 0; i < n; i ++) {
        string s = "";
        s.push_back(a[i]);
        s.push_back(b[i]);
        
        for(int j = 0; j < m; j ++) {
            prefix[i][j] = (i > 0 ? prefix[i - 1][j] : 0) + (s == ADN[j]);
        }
    }
    
    for(int i = 0; i < n; i ++) {
        for(int j = 0; j < k; j ++) {
            sumA[i][j] = (i > 0 ? sumA[i - 1][j] : 0) + (a[i] == ch[j]);
            sumB[i][j] = (i > 0 ? sumB[i - 1][j] : 0) + (b[i] == ch[j]);
        }
    }
}

int get_distance(int x, int y) {
	
	for(int i = 0; i < k; i ++) {
	    int sA = sumA[y][i] - (x > 0 ? sumA[x - 1][i] : 0);
	    int sB = sumB[y][i] - (x > 0 ? sumB[x - 1][i] : 0);
        
        if(sA != sB) return -1;
	}
	
	vector<int> dp(m, 0);
	
	auto get = [&](int l, int r, int i) {
	    return prefix[r][i] - (l > 0 ? prefix[l - 1][i] : 0);
	};
	
	for(int i = 0; i < m; i ++) dp[i] = get(x, y, i);
	
	int total = 0;
	
	for(int i = 0; i < m; i ++) {
        int j = m - 1 - i;
        
        int v = min(dp[i], dp[j]);
        dp[i] -= v;
        dp[j] -= v;
        total += v;
	}
	
    for(int i = 0; i < m; i ++) {
        if(dp[i] == 0) continue ;
        
        for(int j = 0; j < m; j ++) {
            if(dp[j] == 0) continue ;
            
            if(ADN[i][1] == ADN[j][0]) {
                total += dp[i] * 2;
                return total;
            }
        }
    }
	
	return total;
}

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