Submission #944205

#	Time	Username	Problem	Language	Result	Execution time	Memory
944205		Nika533	Paint By Numbers (IOI16_paint)	C++14	90 / 100	2078 ms	164948 KiB

paint

#pragma GCC diagnostic warning "-std=c++11"
#include <bits/stdc++.h>
#include "paint.h"
#define pb push_back
#define MOD 1000000007
#define flush fflush(stdout)
#define all(x) (x).begin(),(x).end()
#define allr(x) (x).rbegin(), (x).rend()
#define pii pair<int,int>
using namespace std;
const int N=200005,K=105;
bool dpPref[N][K],dpSuf[N][K];
int lastBlackPref[N],lastBlackSuf[N],lastDpPref[N][K],lastDpSuf[N][K],L,R;
string solve_puzzle(string s, vector<int> c) {
   int n=s.size(); int k=c.size();
   // build lastBlackPref;
   if (s[0]=='X') lastBlackPref[0]=0;
   else lastBlackPref[0]=-1e9;
   for (int i=1; i<n; i++) {
   	lastBlackPref[i]=lastBlackPref[i-1];
   	if (s[i]=='X') lastBlackPref[i]=i;
	}
	// build lastBlackSuf;
   if (s[n-1]=='X') lastBlackSuf[n-1]=n-1;
   else lastBlackSuf[n-1]=1e9;
   for (int i=n-2; i>=0; i--) {
   	lastBlackSuf[i]=lastBlackSuf[i+1];
   	if (s[i]=='X') lastBlackSuf[i]=i;
	}
   // build dpPref
	int firstBlack=lastBlackSuf[0];
	int lastWhite=-1;
	for (int i=0; i<=min(n-1,firstBlack+c[0]-1); i++) {
		if (s[i]=='_') lastWhite=i;
   	if (i-c[0]+1>lastWhite) dpPref[i][0]=1; 
	}
   for (int ind=1; ind<k; ind++) {
   	lastWhite=-1e9;
   	for (int i=0; i<n; i++) {
   		if (s[i]=='_') lastWhite=i;
   		if (i-c[ind]+1<=lastWhite) continue;
   		if ((i-c[ind])-1<0) continue;
   		if (s[i-c[ind]]=='X') continue;
   		for (int j=max(0,lastBlackPref[(i-c[ind])-1]); j<=(i-c[ind])-1; j++) {
   			if (dpPref[j][ind-1]==1) dpPref[i][ind]=1;
			}
		}
	}
	// build dpSuf
	int lastBlack=lastBlackPref[n-1];
	lastWhite=n;
	for (int i=n-1; i>=max(0,lastBlack-c[k-1]+1); i--) {
		if (s[i]=='_') lastWhite=i;
		if (i+c[k-1]-1<lastWhite) dpSuf[i][k-1]=1;
	}
	for (int ind=k-2; ind>=0; ind--) {
		lastWhite=1e9;
		for (int i=n-1; i>=0; i--) {
			if (s[i]=='_') lastWhite=i;
			if (i+c[ind]-1>=lastWhite) continue;
			if ((i+c[ind])+1>n-1) continue;
			if (s[(i+c[ind])]=='X') continue;
			for (int j=min(n-1,lastBlackSuf[(i+c[ind])+1]); j>=(i+c[ind])+1; j--) {
				if (dpSuf[j][ind+1]==1) dpSuf[i][ind]=1;
			}
		}
	}
	//build lastDpPref
	for (int ind=0; ind<k; ind++) {
		int last=-1;
		for (int i=0; i<n; i++) {
			if (dpPref[i][ind]==1) last=i;
			lastDpPref[i][ind]=last;
		}
	}
	//build lastDpSuf
	for (int ind=0; ind<k; ind++) {
		int last=-1;
		for (int i=0; i<n; i++) {
			if (dpSuf[i][ind]==1) last=i;
			lastDpSuf[i][ind]=last;
		}
	}
	// build answer
	string ans=s;
	for (int i=0; i<n; i++) {
		if (s[i]!='.') continue;
		bool canBeWhite=0,canBeBlack=0;
		// can be '_'
		if (lastBlackPref[i]<0) {
			L=i+1; R=min(n-1,lastBlackSuf[i]);
			if (L<=R && lastDpSuf[R][0]>=L) canBeWhite=1;
//			for (int j=L; j<=R; j++) {
//				if (dpSuf[j][0]==1) canBeWhite=1;
//			}
//			if (canBeWhite==1) cout<<"I "<<i<<" "<<"A"<<endl;
		}
		for (int ind=0; ind<k-1; ind++) {
			bool B1=0,B2=0;
			L=max(0,lastBlackPref[i]); R=i-1;
			if (L<=R && lastDpPref[R][ind]>=L) B1=1;
//			for (int j=L; j<=R; j++) {
//				if (dpPref[j][ind]==1) B1=1;
//			}
			L=i+1; R=min(n-1,lastBlackSuf[i]);
			if (L<=R && lastDpSuf[R][ind+1]>=L) B2=1;
//			for (int j=L; j<=R; j++) {
//				if (dpSuf[j][ind+1]==1) B2=1;
//			}
			if (B1 && B2) canBeWhite=1;
//			if (canBeWhite==1) cout<<"I "<<i<<" "<<ind<<endl;
		}
		if (lastBlackSuf[i]>n-1) {
			L=max(0,lastBlackPref[i]); R=i-1;
			if (L<=R && lastDpPref[R][k-1]>=L) canBeWhite=1;
//			for (int j=L; j<=R; j++) {
//				if (dpPref[j][k-1]==1) canBeWhite=1;
//			}
//			if (canBeWhite==1) cout<<"I "<<i<<" "<<"B"<<endl;
		}
		// can be 'X'
		int lb=-1,rb=n;
		for (int j=i; j>=0; j--) {
			if (s[j]=='_') {
				lb=j; break;
			}
		}
		for (int j=i; j<n; j++) {
			if (s[j]=='_') {
				rb=j; break;
			}
		}
		for (int ind=0; ind<k; ind++) {
			for (int o=0; o<c[ind]; o++) {
				int l=(i-o),r=(i+c[ind]-o-1);
				if (l<0 || r>n-1) continue;
				if (dpPref[r][ind]==1 && dpSuf[l][ind]==1) canBeBlack=1;
			}
		}
		if (canBeBlack==1 && canBeWhite==1) ans[i]='?';
		else if (canBeBlack==1) ans[i]='X';
		else ans[i]='_';
	}
	return ans;
}

Compilation message (stderr)

paint.cpp:1:32: warning: '-std=c++11' is not an option that controls warnings [-Wpragmas]
    1 | #pragma GCC diagnostic warning "-std=c++11"
      |                                ^~~~~~~~~~~~
paint.cpp: In function 'std::string solve_puzzle(std::string, std::vector<int>)':
paint.cpp:122:7: warning: variable 'lb' set but not used [-Wunused-but-set-variable]
  122 |   int lb=-1,rb=n;
      |       ^~
paint.cpp:122:13: warning: variable 'rb' set but not used [-Wunused-but-set-variable]
  122 |   int lb=-1,rb=n;
      |             ^~

• 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