Submission #217431

#	Time	Username	Problem	Language	Result	Execution time	Memory
217431		pit4h	Lamps (JOI19_lamps)	C++14	100 / 100	323 ms	4556 KiB

lamp

#include<bits/stdc++.h>
using namespace std;
int dp[2][4][4][4], dp1[2][4], dp2[2][4][4];
int main() {
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int n;
	string s, t;
	cin>>n>>s>>t;
	for(int i=0; i<=1; ++i) {
		for(int a=0; a<=3; ++a) {
			for(int b=0; b<=3; ++b) {
				for(int c=0; c<=3; ++c) {
					dp[i][a][b][c] = n;
				}
			}
		}
	}
	dp[0][0][0][0]=0;
	for(int a=1; a<=3; ++a) {
		dp1[0][a]=n;
		for(int b=1; b<=3; ++b) {
			dp2[0][a][b]=n;
		}
	}
	for(int i=1; i<=n; ++i) {
		int v1 = n;
		for(int a=0; a<=3; ++a) {
			for(int b=0; b<=3; ++b) {
				for(int c=0; c<=3; ++c) {
					dp[i%2][a][b][c]=n;
					v1 = min(v1, dp[(i+1)%2][a][b][c]);
				}
			}
		}
		if(s[i-1]==t[i-1]) {
			dp[i%2][0][0][0] = v1;
		}
		for(int a=1; a<=3; ++a) {
			if((a==1 && t[i-1]=='0') || (a==2 && t[i-1]=='1') || (a==3 && s[i-1]!=t[i-1])) {
				dp[i%2][a][0][0] = min(v1+1, dp1[(i+1)%2][a]);
			}
			for(int b=1; b<=3; ++b) {
				if(b==a) continue;
				if((a==1 && t[i-1]=='0') || (a==2 && t[i-1]=='1') || (a==3 && ((b==1 && t[i-1]=='1') || (b==2 && t[i-1]=='0')))) {
					dp[i%2][a][b][0] = min(v1+2, min(dp1[(i+1)%2][a], dp1[(i+1)%2][b])+1);
					dp[i%2][a][b][0] = min(dp[i%2][a][b][0], dp2[(i+1)%2][a][b]); 	
				}
				else {
					continue;
				}
				for(int c=1; c<=3; ++c) {
					if(c==a || c==b) continue;
					dp[i%2][a][b][c] = min(v1+3, min(dp1[(i+1)%2][a], min(dp1[(i+1)%2][b], dp1[(i+1)%2][c]))+2);
					dp[i%2][a][b][c] = min(dp[i%2][a][b][c], min(dp2[(i+1)%2][a][b], min(dp2[(i+1)%2][a][c], dp2[(i+1)%2][b][c]))+1);
					dp[i%2][a][b][c] = min(dp[i%2][a][b][c], dp[(i+1)%2][a][b][c]); 	
				}
			}
		}
		for(int a=1; a<=3; ++a) {
			dp1[i%2][a]=n;
			for(int j=0; j<=3; ++j) {
				for(int k=0; k<=3; ++k) {
					dp1[i%2][a] = min(dp1[i%2][a], dp[i%2][a][j][k]);
					dp1[i%2][a] = min(dp1[i%2][a], dp[i%2][j][a][k]);
					dp1[i%2][a] = min(dp1[i%2][a], dp[i%2][j][k][a]);
				}
			}
			for(int b=1; b<=3; ++b) {
				dp2[i%2][a][b]=n;
				for(int j=0; j<=3; ++j) {
					dp2[i%2][a][b] = min(dp2[i%2][a][b], dp[i%2][a][b][j]);
					dp2[i%2][a][b] = min(dp2[i%2][a][b], dp[i%2][j][a][b]);
				}
			}
		}
	}
	int ans = n;
	for(int a=0; a<=3; ++a) {
		for(int b=0; b<=3; ++b) {
			for(int c=0; c<=3; ++c) {
				ans = min(ans, dp[n%2][a][b][c]);
			}
		}
	}
	cout<<ans;
}

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