Submission #52428

#	Time	Username	Problem	Language	Result	Execution time	Memory
52428		polyfish	Paint By Numbers (IOI16_paint)	C++14	100 / 100	414 ms	50836 KiB

paint

//I love armpit fetish
#include <bits/stdc++.h>
using namespace std;

#define debug(x) cerr << #x << " = " << x << '\n';
#define BP() cerr << "OK!\n";
#define PR(A, n) cerr << #A << " = "; for (int _=1; _<=n; ++_) cerr << A[_] << ' '; cerr << '\n';
#define PR0(A, n) cerr << #A << " = "; for (int _=0; _<n; ++_) cerr << A[_] << ' '; cerr << '\n';
#define FILE_NAME "paint"

const int MAX_N = 200007;
const int MAX_K = 107;

int n, k, ps[MAX_N], prevWhite[MAX_N], nextWhite[MAX_N];
vector<int> c;
bool pf[MAX_K][MAX_N], sf[MAX_K][MAX_N], okWhite[MAX_N], okBlack[MAX_N];
string s;

void init() {
	for (int i=1; i<=n; ++i) {
		prevWhite[i] = (s[i]=='_' ? i : prevWhite[i-1]);
	}

	for (int i=n+1; i>=1; --i) {
		nextWhite[i] = (s[i]=='_' ? i : nextWhite[i+1]);
	}
}

void calc_prefix() {
    pf[0][0] = true;
    for (int i=0; i<=k; ++i) {
        for (int j=1; j<=n; ++j) {
            if (s[j]!='X')
                pf[i][j] = pf[i][j-1];
            if (s[j]!='_') {
                int tmp = prevWhite[j];
                if (j-tmp>=c[i] && s[j-c[i]]!='X') {
                    pf[i][j] = pf[i][j] || pf[i-1][max(0, j-c[i]-1)];
                }
            }
        }
    }
}

void calc_suffix() {
    sf[k+1][n+1] = true;
    for (int i=k+1; i>0; --i) {
        for (int j=n; j>=1; --j) {
            if (s[j]!='X')
                sf[i][j] = sf[i][j+1];
            if (s[j]!='_') {
                int tmp = nextWhite[j];
                if (tmp-j>=c[i] && s[j+c[i]]!='X') {
                    sf[i][j] = sf[i][j] || sf[i+1][min(n+1, j+c[i]+1)];
                }
            }
        }
    }
}

void checkWhiteSolution() {
    for (int i=1; i<=n; ++i) {
        if (s[i]=='X')
            continue;
        for (int j=0; j<=k; ++j) {
            okWhite[i] = okWhite[i] || (pf[j][i-1] && sf[j+1][i+1]);
        }
    }
}

void checkBlackSolution() {
    for (int i=1; i<=k; ++i) {
        for (int j=1; j+c[i]-1<=n; ++j) {
            if (nextWhite[j]>j+c[i]-1 && s[j-1]!='X'
                && s[j+c[i]]!='X' && pf[i-1][max(0, j-2)]
                && sf[i+1][min(n+1, j+c[i]+1)]) {
                ++ps[j]; --ps[j+c[i]];
            }
        }
    }
    for (int i=1; i<=n; ++i) {
        ps[i] += ps[i-1];
        if (ps[i])
            okBlack[i] = true;
    }
}

string solve_puzzle(string _s, vector<int> _c) {
	n = _s.size();
	s = '_' + _s + '_';
	k = _c.size();
	c = _c;
	c.insert(c.begin(), 0);
	c.push_back(0);
	init();
	calc_prefix();
    calc_suffix();
    checkWhiteSolution();
    checkBlackSolution();
    string res;
    for (int i=1; i<=n; ++i) {
        if (okWhite[i] && okBlack[i])
            res += '?';
        else if (okWhite[i])
            res += '_';
        else
            res += 'X';
    }
    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