Submission #211708

#	Time	Username	Problem	Language	Result	Execution time	Memory
211708		nvmdava	Building 4 (JOI20_building4)	C++17	100 / 100	389 ms	44536 KiB

building4

#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define ll long long
#define ff first
#define ss second
#define N 1050000
#define MOD 998244353
#define INF 0x3f3f3f3f

int a[N][2];
int dp[N][2][2];

void update(int i, int j, int mn, int mx){
	if(mx == -1) return;
	if(dp[i][j][0] == -1){
		dp[i][j][0] = mn + j;
		dp[i][j][1] = mx + j;
		return;
	}
	dp[i][j][0] = min(dp[i][j][0], mn + j); 
	dp[i][j][1] = max(dp[i][j][1], mx + j); 
}

int ans[N];

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n;
    cin>>n;
    for(int i = 1; i <= n * 2; ++i)
    	cin>>a[i][0];
    for(int i = 1; i <= n * 2; ++i)
    	cin>>a[i][1];
    memset(dp, -1, sizeof dp);
   	memset(dp[0], 0, sizeof dp[0]);
    for(int i = 1; i <= n * 2; ++i){
    	for(int j0 = 0; j0 < 2; ++j0){
    		for(int j1 = 0; j1 < 2; ++j1){
    			if(a[i][j1] >= a[i - 1][j0])
    				update(i, j1, dp[i - 1][j0][0], dp[i - 1][j0][1]);
    		}
    	}
    }
    int la = -1, c = n;
    if(dp[2 * n][0][0] <= c && c <= dp[2 * n][0][1])
    	la = 0;

   	if(dp[2 * n][1][0] <= c && c <= dp[2 * n][1][1])
   		la = 1;

   	if(la == -1){
   		cout<<-1;
   		return 0;
   	}
    for(int i = n * 2; i >= 0; --i){
    	ans[i] = la;
    	c -= la;
    	for(int j = 0; j < 2; ++j){
    		if(a[i - 1][j] <= a[i][la]){
    			if(dp[i - 1][j][0] <= c && c <= dp[i - 1][j][1]){
    				la = j;
    				break;
    			}
    		}
    	}
    }
    for(int i = 1; i <= 2 * n; ++i)
    	cout<<(ans[i] == 0 ? "A" : "B");
}

Compilation message (stderr)

building4.cpp: In function 'int main()':
building4.cpp:49:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
     if(dp[2 * n][0][0] <= c && c <= dp[2 * n][0][1])
     ^~
building4.cpp:52:5: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
     if(dp[2 * n][1][0] <= c && c <= dp[2 * n][1][1])
     ^~

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