Submission #393707

#	Time	Username	Problem	Language	Result	Execution time	Memory
393707		JimmyZJX	Unscrambling a Messy Bug (IOI16_messy)	C++14	100 / 100	3 ms	460 KiB

messy

#include <iostream>
#include <fstream>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cassert>
#include <tuple>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <unordered_set>
#include <unordered_map>
#include <numeric>

using namespace std;

typedef long long LL;
typedef vector<int> Vi;
typedef vector<LL> VL;
typedef vector<bool> Vb;
typedef vector<vector<int>> Vii;
typedef vector<vector<vector<int>>> Viii;
typedef vector<vector<pair<int, int>>> Vip;

#define forR(i, n) for (int i = 0; i < (n); i++)

void add_element(string x);
void compile_set();
bool check_element(string x);

int N;
Vi p;

void guess(int l, int r, Vi digits) { // original [l, r] <-> digits
	if (l == r) {
		assert(digits.size() == 1);
		p[digits[0]] = l;
		return;
	}

	Vi left, right;
	for (int t : digits) { // test t
		string s(N, '0');
		for (int k : digits) {
			if (k != t) {
				s[k] = '1';
			}
		}
		if (check_element(s)) {
			// t is in left
			left.push_back(t);
		} else {
			right.push_back(t);
		}
	}

	int mid = l + r >> 1;
	guess(l, mid, left);
	guess(mid + 1, r, right);
}

void s1(int l, int r) {
	if (l == r) return;
	int mid = l + r >> 1;
	// label [l .. mid] seperately

	for (int t = l; t <= mid; t++) {
		string s(N, '0'); // 11011111 11111111
		for (int k = l; k <= r; k++) {
			if (k != t) {
				s[k] = '1';
			}
		}
		add_element(s);
	}

	s1(l, mid);
	s1(mid + 1, r);
}

Vi restore_permutation(int n, int w, int r) {
	N = n;
	p = Vi(n, -1);

	//for (int i = 1; i <= n; i++) {
	//	// i*0 + (n-i)*1
	//	string s;
	//	s.append(i, '0');
	//	s.append(n - i, '1');
	//	add_element(s);
	//}
	//compile_set();

	//string cur; cur.append(n, '1');
	//Vi p(n);
	//for (int i = 0; i < n; i++) {
	//	forR(j, n) {
	//		if (cur[j] == '0') continue;
	//		cur[j] = '0';
	//		if (check_element(cur)) {
	//			// j-th is original i
	//			p[j] = i;
	//			break;
	//		}
	//		cur[j] = '1';
	//	}
	//}
	s1(0, n - 1);
	compile_set();

	Vi seq; forR(i, n) seq.push_back(i);
	guess(0, n - 1, seq);
	
	return p;
}

#ifdef TEST_LOCAL
Vi _p { 2,1,3,0 };
set<string> _comp;
void add_element(string x) {
	string y;
	for (int d : _p) {
		y.append(1, x[d]);
	}
	_comp.insert(y);
}
void compile_set() {}
bool check_element(string x) {
	return _comp.count(x) > 0;
}

int main() {
	auto r = restore_permutation(4, 16, 16);

	return 0;
}
#endif

Compilation message (stderr)

messy.cpp: In function 'void guess(int, int, Vi)':
messy.cpp:60:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   60 |  int mid = l + r >> 1;
      |            ~~^~~
messy.cpp: In function 'void s1(int, int)':
messy.cpp:67:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   67 |  int mid = l + r >> 1;
      |            ~~^~~

• Subtask 1: 20 / 20
• Subtask 2: 18 / 18
• Subtask 3: 11 / 11
• Subtask 4: 21 / 21
• Subtask 5: 30 / 30