Submission #828453

#	Time	Username	Problem	Language	Result	Execution time	Memory
828453		caganyanmaz	Paint By Numbers (IOI16_paint)	C++14	100 / 100	174 ms	16160 KiB

paint

#include <bits/stdc++.h>
#include "paint.h"

#ifdef DEBUGGING
#include "../debug.h"
#else
#define debug(x...) void(42)
#endif

using namespace std;

constexpr static int INF = 1e9;


constexpr static int MXN = 2e5 + 5;
constexpr static int MXK = 105;


bitset<MXK> dp[2][MXN][2]; // Valid for left/right, ending pos, whether it ends there or it ended before
int wpf[MXN], bpf[MXN];
int pf[MXN];


static inline int white(int l, int r)
{
	return wpf[r] - wpf[l];
}

static inline int black(int l, int r)
{
	return bpf[r] - bpf[l];
}

string solve_puzzle(string s, vector<int> c)
{
	int n = s.size(), k = c.size();
	debug(n, k);
	for (int i = 1; i <= n; i++)
	{
		if (s[i-1] == '_') wpf[i]++;
		else if (s[i-1] == 'X') bpf[i]++;
		wpf[i] += wpf[i-1];
		bpf[i] += bpf[i-1];
	}
	// Left iteration
	dp[0][0][0][0] = 1;
	for (int i = 1; i <= n; i++)
	{
		dp[0][i][0][0] = dp[0][i-1][0][0] && s[i-1] != 'X'; // New ended or ended before 
		for (int j = 1; j <= k; j++)
		{
			int sz = c[j-1]; 
			if (i-sz >= 0 && dp[0][i-sz][0][j-1] && white(i-sz, i) == 0)
			{
				debug(0, i, j);
				dp[0][i][1][j] = true;
			}
			dp[0][i][0][j] = (dp[0][i-1][1][j] || dp[0][i-1][0][j]) && s[i-1] != 'X'; // New ended or ended before 
		}
	}
	// Right iteration
	dp[1][n][0][k] = 1;
	for (int i = n-1; i >= 0; i--)
	{
		dp[1][i][0][k] = dp[1][i+1][0][k] && s[i] != 'X';
		for (int j = k-1; j >= 0; j--)
		{
			int sz = c[j];
			if (i+sz <= n && dp[1][i+sz][0][j+1] && white(i, i+sz) == 0)
			{
				debug(1, i, j);
				dp[1][i][1][j] = true;
			}
			dp[1][i][0][j] = (dp[1][i+1][1][j] || dp[1][i+1][0][j]) && s[i] != 'X';
		}
	}
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j <= k-1; j++)
		{
			if (i+c[j] <= n && dp[0][i+c[j]][1][j+1] && dp[1][i][1][j])
			{
				pf[i]++;
				pf[i+c[j]]--;
			}
		}
	}
	for (int i = 1; i < n; i++)
		pf[i] += pf[i-1];
	string res(n, '0');
	for (int i = 0; i < n; i++)
	{
		bool white_possible = false;
		for (int j = 0; j <= k; j++)
		{
			if ((dp[0][i+1][0][j] && dp[1][i][0][j]))
			{
				debug(i, j);
				white_possible = true;
			}
		}
		bool black_possible = pf[i] > 0;
		debug(i, white_possible, black_possible);
		if (white_possible && black_possible)
			res[i] = '?';
		else if (white_possible)
			res[i] = '_';
		else 
			res[i] = 'X';
		assert(white_possible || black_possible);
	}
	return res;
}

• Subtask 1: 7 / 7
• Subtask 2: 3 / 3
• Subtask 3: 22 / 22
• Subtask 4: 27 / 27
• Subtask 5: 21 / 21
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10