Submission #823103

#	Time	Username	Problem	Language	Result	Execution time	Memory
823103		TheOpChicken	Lamps (JOI19_lamps)	C++17	4 / 100	193 ms	67064 KiB

lamp

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

/*
0 = nothing. 
1 = toggle
2 = set 0s
3 = set 1s
0: 0 0 0
1: 0 0 1
2: 0 0 2
3: 0 0 3
4: 0 1 2
5: 0 1 3
6: 0 2 1
7: 0 2 3
8: 0 3 1
9: 0 3 2
10: 1 2 3
11: 1 3 2
12: 2 1 3
13: 2 3 1
14: 3 1 2
15: 3 2 1
*/


const int maxN = 1e6 + 5, inf = 1e9;
int dp[maxN][16];

bool res[16][2] = {{0, 1}, {1, 0}, {1, 1}, {0, 0}, {0, 0}, {1, 1}, {1, 1}, {1, 1}, {0, 0}, {0, 0}, {1, 1}, {0, 0}, {1, 1}, {0, 0}, {0, 0}, {1, 1}};

vector<vector<int> > ops = {{}, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 1}, {2, 3}, {3, 1}, {3, 2}, {1, 2, 3}, {1, 3, 2}, {2, 1, 3}, {2, 3, 1}, {3, 1, 2}, {3, 2, 1}};

int ops_needed[16][16];

int lcs(vector<int> X, vector<int> Y)
{
    int m = X.size();
    int n = Y.size();
    int L[m + 1][n + 1];
 
    for (int i = 0; i <= m; i++) {
        for (int j = 0; j <= n; j++) {
            if (i == 0 || j == 0)
                L[i][j] = 0;
 
            else if (X[i - 1] == Y[j - 1])
                L[i][j] = L[i - 1][j - 1] + 1;
 
            else
                L[i][j] = max(L[i - 1][j], L[i][j - 1]);
        }
    }

    return L[m][n];
}

int main(){
	for (int i = 0; i < 16; i++){
		for (int j = 0; j < 16; j++){
			ops_needed[i][j] = ops[j].size() - lcs(ops[i], ops[j]);
		}
	}

	int n;
	cin >> n;

	string a, b;
	cin >> a >> b;

	dp[0][0] = 0;
	for (int i = 1; i < 16; i++) dp[0][i] = inf;

	for (int i = 1; i <= n; i++){
		bool a_bit = a[i-1] - '0', b_bit = b[i-1] - '0';
		for (int j = 0; j < 16; j++){
			dp[i][j] = inf;
			if (res[a_bit][j] != b_bit) continue;
			for (int k = 0; k < 16; k++) dp[i][j] = min(dp[i][j], dp[i-1][k] + ops_needed[k][j]);
		}
	}

	int ans = inf;
	for (int i = 0; i < 16; i++) ans = min(ans, dp[n][i]);

	cout << ans << endl;
}

Compilation message (stderr)

lamp.cpp: In function 'int main()':
lamp.cpp:79:20: warning: iteration 2 invokes undefined behavior [-Waggressive-loop-optimizations]
   79 |    if (res[a_bit][j] != b_bit) continue;
      |        ~~~~~~~~~~~~^
lamp.cpp:77:21: note: within this loop
   77 |   for (int j = 0; j < 16; j++){
      |                   ~~^~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 4 / 4
• Subtask 4: 0 / 49