Submission #63310

#	Time	Username	Problem	Language	Result	Execution time	Memory
63310		fallingstar	Paint By Numbers (IOI16_paint)	C++14	100 / 100	415 ms	49120 KiB

paint

#include "paint.h"
#include <algorithm>

using namespace std;

const int N = 2e5 + 2;
const int K = 1e2 + 2;

int n, k, sumW[N], c[N];
bool canPref[N][K], canSuff[N][K];
string s;
bool canBlack[N], canWhite[N];

inline bool GetPref(int i, int j)
{
	if (i <= 0) return j == 0;
	else return s[i] != 'X' && canPref[i - 1][j];
}
inline bool GetSuff(int i, int j)
{
	if (i > n) return j == k + 1;
	else return s[i] != 'X' && canSuff[i + 1][j];
}

void Preprocess()
{
	for (int i = 1; i <= n; ++i)
		sumW[i] = sumW[i - 1] + (s[i] == '_');

	canPref[0][0] = canSuff[n + 1][k + 1] = true;

	for (int i = 1; i <= n; ++i)
		for (int j = 0; j <= k; ++j)
		{
			// place white
			canPref[i][j] = canPref[i - 1][j] && s[i] != 'X';
			// place black
			if (j > 0)
				canPref[i][j] |= i >= c[j] && sumW[i] == sumW[i - c[j]] && GetPref(i - c[j], j - 1);
		}

	for (int i = n; i >= 1; --i)
		for (int j = 1; j <= k + 1; ++j)
		{
			// place white
			canSuff[i][j] = canSuff[i + 1][j] && s[i] != 'X';
			// place black
			if (j > 0)
				canSuff[i][j] |= i + c[j] - 1 <= n && sumW[i - 1] == sumW[i + c[j] - 1] && GetSuff(i + c[j], j + 1);
		}
}

string solve_puzzle(string _s, vector<int> _c) {
	n = _s.size(), k = _c.size();
	s = " " + _s, copy(_c.begin(), _c.end(), c + 1);

	Preprocess();

	for (int i = 1, r = 0; i <= n; ++i)
	{
		if (s[i] != 'X')
		{
			for (int j = 0; j <= k; ++j)
				if (canPref[i - 1][j] && canSuff[i + 1][j + 1])
				{
					canWhite[i] = true;
					break;
				}
		}
		else canBlack[i] = true;

		if (s[i] != '_')
		{
			for (int j = 1; j <= k; ++j)
				if (GetPref(i - 1, j - 1) && i + c[j] - 1 <= n && sumW[i - 1] == sumW[i + c[j] - 1] && GetSuff(i + c[j], j + 1))
					r = max(r, i + c[j] - 1);

			if (r >= i) canBlack[i] = true;
		}
		else canWhite[i] = true;
	}

	for (int i = 1; i <= n; ++i)
		if (canBlack[i] && canWhite[i]) _s[i - 1] = '?'; else
		if (canBlack[i]) _s[i - 1] = 'X';
		else _s[i - 1] = '_';

    return _s;
}

• 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