Submission #217887

#	Time	Username	Problem	Language	Result	Execution time	Memory
217887		georgerapeanu	Building 4 (JOI20_building4)	C++11	100 / 100	404 ms	45300 KiB

building4

#include <cstdio>
#include <iostream>
#include <algorithm>

using namespace std;

int n;
pair<int,int> dp[1000005][2];
int v[1000005][2];

int main(){

    scanf("%d",&n);

    for(int h = 0;h < 2;h++){
        for(int i = 1;i <= 2 * n;i++){
            scanf("%d",&v[i][h]);
        }
    }

    dp[1][0] = {0,0};
    dp[1][1] = {1,1};

    for(int i = 2;i <= 2 * n;i++){
        for(int h = 0;h < 2;h++){
            dp[i][h] = {1e9,0};
            for(int h2 = 0;h2 < 2;h2++){
                if(v[i - 1][h2] <= v[i][h]){
                    dp[i][h].first = min(dp[i][h].first,dp[i - 1][h2].first + h);
                    dp[i][h].second = max(dp[i][h].second,dp[i - 1][h2].second + h);
                }
            }
        }
    }
    
    for(int h = 0;h < 2;h++){
        if(dp[n * 2][h].first <= n && n <= dp[n * 2][h].second){
            int x = 2 * n,y = n;
            string ans(2 * n,' ');
            while(x){
                ans[x - 1] = (h == 1) + 'A';
                y -= h;
                x--;
                if(v[x][0] <= v[x + 1][h] && dp[x][0].first <= y && y <= dp[x][0].second){
                    h = 0;
                }
                else{
                    h = 1;
                }
            }
            cout << ans << endl;;
            return 0;
        }
    }

    cout << -1 << endl;

    return 0;
}

Compilation message (stderr)

building4.cpp: In function 'int main()':
building4.cpp:13:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
building4.cpp:17:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d",&v[i][h]);
             ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 89 / 89