Submission #67186

#	Time	Username	Problem	Language	Result	Execution time	Memory
67186		radoslav11	Xylophone (JOI18_xylophone)	C++14	100 / 100	132 ms	720 KiB

xylophone

#include <bits/stdc++.h>
#include "xylophone.h"
//#include "Lgrader.cpp"
 
using namespace std;
template<class T, class T2> inline int chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline int chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const int MAXN = (5042);
 
int n;
 
bool check(vector<int> p)
{
	vector<bool> used(p.size(), 0);
 
	int pmax, pmin, mx = -1, mn = (int)1e9;
	for(int i = 0; i < n; i++)
	{
		if(chkmax(mx, p[i])) pmax = i;
		if(chkmin(mn, p[i])) pmin = i;
	
		if(p[i] >= n) return false;
		if(used[p[i]]) return false;
		used[p[i]] = true;
	}
 
	if((mx != (int)p.size() - 1) || mn != 0 || pmax < pmin)
		return false;
 
	return true;
}
 
int ask(int l, int r) { return query(l + 1, r + 1); }
 
void fix(vector<int> &p)
{
	int mn = 1e9;
	for(int &x: p)
		chkmin(mn, x);
 
	for(int &x: p)
		x += -mn;
 
	//for(int x: p)
	//	cerr << x << " ";
	//cerr << endl << flush;
}
 
int ask2[MAXN], ask3[MAXN];
 
int my_ask(int a, int b, int c)
{
	int ret = 0;
	
	chkmax(ret, a - b);
	chkmax(ret, b - a);
 
	chkmax(ret, a - c);
	chkmax(ret, c - a);
 
	chkmax(ret, c - b);
	chkmax(ret, b - c);
 
	return ret;
}
 
void solve(int N) 
{
	n = N;
 
	for(int i = 0; i + 1 < n; i++) ask2[i] = ask(i, i + 1);
	for(int i = 0; i + 2 < n; i++) ask3[i] = ask(i, i + 2);
 
	vector<int> A(n, 0);
	A[0] = 0;
	A[1] = ask2[0];
 
	for(int i = 2; i < n; i++)
	{
		if(my_ask(A[i - 2], A[i - 1], A[i - 1] + ask2[i - 1]) == ask3[i - 2]) A[i] = A[i - 1] + ask2[i - 1];
		else A[i] = A[i - 1] - ask2[i - 1];
	}
 
	fix(A);
	if(check(A))
	{
		for(int i = 0; i < n; i++)
			answer(i + 1, A[i] + 1);
		return;
	}
 
	A.assign(n, 0);
	A[0] = 0;
	A[1] = -ask2[0];
 
	for(int i = 2; i < n; i++)
	{
		if(my_ask(A[i - 2], A[i - 1], A[i - 1] + ask2[i - 1]) == ask3[i - 2]) A[i] = A[i - 1] + ask2[i - 1];
		else A[i] = A[i - 1] - ask2[i - 1];
	}
 
	fix(A);
	if(check(A))
	{
		for(int i = 0; i < n; i++)
			answer(i + 1, A[i] + 1);
		return;
	}
}

Compilation message (stderr)

xylophone.cpp: In function 'bool check(std::vector<int>)':
xylophone.cpp:27:42: warning: 'pmin' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if((mx != (int)p.size() - 1) || mn != 0 || pmax < pmin)
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
xylophone.cpp:27:42: warning: 'pmax' may be used uninitialized in this function [-Wmaybe-uninitialized]

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