Submission #301387

#	Time	Username	Problem	Language	Result	Execution time	Memory
301387		williamMBDK	Paint By Numbers (IOI16_paint)	C++17	90 / 100	2029 ms	106360 KiB

paint

#include<bits/stdc++.h>
#include "paint.h"
#include <cstdlib>
using namespace std;
struct BIT{
	int N;
	vector<int> arr;
	BIT(){}
	BIT(int n){
		N = n + 1;
		arr = vector<int> (N);
	}
	void _u(int i, int val){
		if(i < N) arr[i] += val;
	}
	void u(int a, int b){
		a++;
		b++;
		_u(b+1,-1);
		_u(a,1);
	}
	void start(){
		for(int i = 1; i < N; i++) arr[i] += arr[i-1];
	}
	int q(int i){
		i++;
		return arr[i];
	}
};
const int MN = 200000;
int N, K;
string S;
vector<int> C;
vector<vector<int>> dp (MN + 10, vector<int> (101, -1));
vector<int> pref (MN), pref2(MN);
BIT bitx, bitw;
int rec(int i1, int i2){
	if(dp[i1][i2] != -1) return dp[i1][i2];
	if(i2 == K){
		dp[i1][i2] = 1;
		if(i1 >= N) return 1;
		int c = pref2[N-1] - (i1 == 0 ? 0 : pref2[i1-1]);
		dp[i1][i2] = c == 0;
		if(dp[i1][i2]){
			bitw.u(i1,N-1);
		}
		return dp[i1][i2];
	}
	dp[i1][i2] = 0;
	if(i1 + C[i2] - 1 >= N) return dp[i1][i2];
	int c = pref[i1 + C[i2] - 1] - (i1 == 0 ? 0 : pref[i1-1]);
	int t = i1 + C[i2];
	if(c == 0 && (t == N || S[t] != 'X') && rec(i1 + C[i2] + 1, i2+1)){
		if(t < N){
			bitw.u(t,t);
		}
		bitx.u(i1,i1+C[i2]-1);
		dp[i1][i2] = 1;
	}
	if(S[i1] != 'X' && rec(i1 + 1, i2)){
		bitw.u(i1,i1);
		dp[i1][i2] = 1;
	}
	//cout << i1 << " " << i2 << " " << dp[i1][i2] << endl;
	return dp[i1][i2];
}
string solve_puzzle(string _s, vector<int> _c) {
	//cout << "input: " << _s << endl;
	S = _s;
	C = _c;
	//for(auto e : C) cout << e << " ";
	//cout << endl;
	N = S.length();
	K = C.size();
	pref[0] = (S[0] == '_');
	for(int i = 1; i < N; i++){
		pref[i] = pref[i-1] + (S[i] == '_');
	}
	pref2[0] = (S[0] == 'X');
	for(int i = 1; i < N; i++){
		pref2[i] = pref2[i-1] + (S[i] == 'X');
	}
	bitx = BIT(N);
	bitw = BIT(N);
	rec(0, 0);
	string res (N, '?');
	bitx.start();
	bitw.start();
	for(int i = 0; i < N; i++){
		/*if(S[i] == 'X') x[i] = 1;
		else if(S[i] == '_') w[i] = 1;
		if(w[i] == 0 && x[i] == 0) w[i] = 1;*/
		int tx = bitx.q(i);
		int tw = bitw.q(i);
		if(tx > 0 && tw == 0) res[i] = 'X';
		else if(tx == 0 && tw > 0) res[i] = '_';
	}
	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: 0 / 10