Submission #391351

#	Time	Username	Problem	Language	Result	Execution time	Memory
391351		qwerasdfzxcl	Lamps (JOI19_lamps)	C++14	4 / 100	29 ms	16076 KiB

lamp

#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
string x, y;
int dp[1001000][3];

int calc(int n){
    for (int i=0;i<n;i++) dp[i][0] = 1e9, dp[i][1] = 1e9, dp[i][2] = 1e9;
    dp[0][0] = 1;
    if (x[0]!=y[0]) dp[0][1] = 1, dp[0][2] = 1;
    else dp[0][2] = 0;
    for (int i=1;i<n;i++){
        if (x[i]==y[i]){
            if (y[i-1]!=y[i]) dp[i][0] = dp[i-1][2]+1;
            else dp[i][0] = min(dp[i-1][0], dp[i-1][2]+1);
            dp[i][2] = dp[i-1][2];
        }
        else{
            if (y[i-1]!=y[i]) dp[i][0] = dp[i-1][2]+1;
            else dp[i][0] = min(dp[i-1][0], dp[i-1][2]+1);
            if (x[i-1]==y[i-1]) dp[i][1] = dp[i-1][2]+1;
            else dp[i][1] = min(dp[i-1][2]+1, dp[i-1][1]);
            dp[i][2] = min(dp[i][0], dp[i][1]);
        }
    }
    //for (int i=0;i<n-1;i++) cout << dp[i][2];
    return dp[n-1][2];
}

int main(){
    cin.tie(NULL);
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n >> x >> y;
    int ans = calc(n);
    int pt1=-1, pt2=-1;
    for (int i=0;i<n;i++) if(x[i]!=y[i]){
        pt1=i; break;
    }
    for (int i=n-1;i>=0;i--) if(x[i]!=y[i]){
        pt2=i; break;
    }
    if (pt1!=-1){
        for (int i=pt1;i<=pt2;i++){
            if (x[i]=='0') x[i] = '1';
            else x[i] = '0';
        }
        ans = min(ans, calc(n)+1);
    }
    cout << ans;
    return 0;
}

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