Submission #1322880

#TimeUsernameProblemLanguageResultExecution timeMemory
1322880adiyerXylophone (JOI18_xylophone)C++20
100 / 100
71 ms508 KiB
#include "xylophone.h"
#include <bits/stdc++.h>

using namespace std;

static int a[5005];

int dp[5005][2], pos[5005], cnt[5005];

bool was[5005];

void solve(int n){
	
	for(int i = 1; i < n; i++) dp[i][0] = query(i, i + 1);
	for(int i = 1; i + 1 < n; i++) dp[i][1] = query(i, i + 2);

	bool good = 0;

	for(int r = 2; r <= n; r++){
		for(int i = 1; i <= n; i++) was[i] = cnt[i] = pos[i] = a[i] = 0;
		bool ok = 1;
		int l = r - 1;

		a[r] = n, was[a[r]] = 1;
		a[l] = n - dp[l][0], was[a[l]] = 1;
		
		if(r < n) a[r + 1] = n - dp[r][0], was[a[r + 1]] = 1;

		for(int i = l - 1; i >= 1; i--){
			a[i] = a[i + 1] - dp[i][0];
			if(a[i] < 0 || a[i] > n || was[a[i]]){
				a[i] = a[i + 1] + dp[i][0];
				if(a[i] < 0 || a[i] > n || was[a[i]]){
					ok = 0;
					break;
				}
				was[a[i]] = 1;
				continue;
			}
			if(dp[i][0] == abs(a[i + 1] - a[i]) 
			&& dp[i][1] == max({a[i], a[i + 1], a[i + 2]}) - min({a[i], a[i + 1], a[i + 2]})
			&& dp[i + 1][0] == abs(a[i + 2] - a[i + 1])){
				was[a[i]] = 1;
				continue;
			}
			a[i] = a[i + 1] + dp[i][0];
			if(a[i] < 0 || a[i] > n || was[a[i]]){
				ok = 0;
				break;
			}
			was[a[i]] = 1;
		}

		if(!ok) continue;

		for(int i = r + 2; i <= n; i++){
			a[i] = a[i - 1] - dp[i - 1][0];
			if(a[i] < 0 || a[i] > n || was[a[i]]){
				a[i] = a[i - 1] + dp[i - 1][0];
				if(a[i] < 0 || a[i] > n || was[a[i]]){
					ok = 0;
					break;
				}
				was[a[i]] = 1;
				continue;
			}
			if(dp[i - 1][0] == abs(a[i] - a[i - 1]) 
			&& dp[i - 2][1] == max({a[i], a[i - 1], a[i - 2]}) - min({a[i], a[i - 1], a[i - 2]})
			&& dp[i - 2][0] == abs(a[i - 2] - a[i - 1])){
				was[a[i]] = 1;
				continue;
			}
			a[i] = a[i - 1] + dp[i - 1][0];
			if(a[i] < 0 || a[i] > n || was[a[i]]){
				ok = 0;
				break;
			}
			was[a[i]] = 1;
		}

		if(!ok) continue;

		for(int i = 2; i <= n; i++){
			if(abs(a[i] - a[i - 1]) != dp[i - 1][0]) ok = 0;
			if(i >= 3 && max({a[i], a[i - 1], a[i - 2]}) - min({a[i], a[i - 1], a[i - 2]}) != dp[i - 2][1]) ok = 0;
		}

		for(int i = 1; i <= n; i++) ok &= (a[i] <= n), ok &= (a[i] >= 1); 
		
		if(ok){
			for(int i = 1; i <= n; i++) pos[a[i]] = i, cnt[a[i]]++;
			for(int i = 1; i <= n; i++) ok &= (cnt[i] == 1);
			ok &= (pos[1] < pos[n]);
		}

		if(ok){
			good = 1;
			break;
		}
	}

	for(int i = 1; i <= n; i++){
		answer(i, a[i]);
	}
}
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