Submission #391671

#	Time	Username	Problem	Language	Result	Execution time	Memory
391671		qwerasdfzxcl	Lamps (JOI19_lamps)	C++14	4 / 100	42 ms	14164 KiB

lamp

#include <bits/stdc++.h>
 
typedef long long ll;
using namespace std;
string x, y;
int dp[1001000][3];
 
int calc(int n){
    int pt[2] = {-2, -2}, pt2=-2;
    if (x[0]!=y[0]) dp[0][0]=1, pt2=0;
    dp[0][1] = 1;
    pt[y[0]-'0']=0;
    for (int i=1;i<n;i++){
        if (x[i]==y[i]) dp[i][0]=min(dp[i-1][0], dp[i-1][1]);
        else{
            if (x[i-1]!=y[i-1]) dp[i][0] = min(dp[i-1][0], dp[i-1][1]+1);
            else if (pt2==-2) dp[i][0] = min(dp[i-1][0], dp[i-1][1])+1;
            else dp[i][0] = min(min(dp[i-1][0], dp[i-1][1]), dp[pt2][0])+1;
            pt2=i;
        }
        if (y[i-1]==y[i]) dp[i][1] = min(dp[i-1][1], dp[i-1][0]+1), pt[y[i]-'0']=i;
        else{
            if (pt[y[i]-'0']==-2) dp[i][1] = min(dp[i-1][0], dp[i-1][1])+1;
            else dp[i][1] = min(min(dp[i-1][0], dp[i-1][1]), dp[pt[y[i]-'0']][1])+1;
            pt[y[i]-'0']=i;
        }
    }
    /*for (int i=0;i<n;i++) cout << dp[i][0] << ' ';
    cout << '\n';
    for (int i=0;i<n;i++) cout << dp[i][1] << ' ';
    cout << '\n';*/
    return min(dp[n-1][0], dp[n-1][1]);
}
 
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);
    }
    for (int j=0;j<2;j++){
        for (int i=0;i<n;i++) x[i] = '0'+j;
        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