Submission #70789

#	Time	Username	Problem	Language	Result	Execution time	Memory
70789		dnass	Xylophone (JOI18_xylophone)	C++14	100 / 100	82 ms	704 KiB

xylophone

#include "xylophone.h"
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int n;
int a[5010];
bool found[5010];
int place_1, place_n;

int bin_search_n(int l, int r){
	if(l==r) return l;
	if(l+1==r){
		int x = query(1, r);
		if(x==n-1) return r;
		else return l;
	}
	int mid = (l+r)/2;
	int x = query(1, mid);
	if(x<n-1) return bin_search_n(mid+1, r);
	else return bin_search_n(l, mid);
}

int bin_search_1(int l, int r){
	if(l==r) return l;
	if(l+1==r){
		int x = query(r, n);
		if(x==n-1) return r;
		else return l;
	}
	int mid = (l+r)/2;
	int x = query(mid, n);
	if(x<n-1) return bin_search_1(l, mid-1);
	else return bin_search_1(mid, r);
}

void solve(int N) {
	n = N;
	memset(found, false, sizeof found);
	//place_n = bin_search_n(1, n); a[place_n] = n; found[n] = true;
	place_1 = bin_search_1(1, n); a[place_1] = 1; found[1] = true;
	for(int i=place_1-1;i>0;i--){
		int x = query(i, i+1);
		int mx = a[i+1]+x, mn = a[i+1]-x;
		if(mx>n||found[mx]){
			a[i] = mn;
			found[mn] = true;
		}else if(mn<1||found[mn]){
			a[i] = mx;
			found[mx] = true;
		}else{
			int y = query(i, i+2);
			if(a[i+2]>a[i+1]){
				if(y==a[i+2]-mn){
					a[i] = mn;
					found[mn] = true;
				}else{
					a[i] = mx;
					found[mx] = true;
				}
			}else{
				if(y==mx-a[i+2]){
					a[i] = mx;
					found[mx] = true;
				}else{
					a[i] = mn;
					found[mn] = true;
				}
			}
		}
	}
	for(int i=place_1+1;i<=n;i++){
		//if(i==place_n) continue;
		int x = query(i-1, i);
		int mx = a[i-1]+x, mn = a[i-1]-x;
		//printf("a[i-1]: %d, mn: %d, mx: %d\n", a[i-1], mn, mx);
		if(mx>n||found[mx]){
			a[i] = mn;
			found[mn] = true;
		}else if(mn<1||found[mn]){
			a[i] = mx;
			found[mx] = true;
		}else{
			int y = query(i-2, i);
			if(a[i-2]>a[i-1]){
				if(y==a[i-2]-mn){
					a[i] = mn;
					found[mn] = true;
				}else{
					a[i] = mx;
					found[mx] = true;
				}
			}else{
				if(y==mx-a[i-2]){
					a[i] = mx;
					found[mx] = true;
				}else{
					a[i] = mn;
					found[mn] = true;
				}
			}
		}
	}
	for(int i=1;i<=n;i++){
		//printf("%d ", a[i]);
		answer(i, a[i]);
	}
}

• Subtask 1: 11 / 11
• Subtask 2: 36 / 36
• Subtask 3: 53 / 53