Submission #219474

#	Time	Username	Problem	Language	Result	Execution time	Memory
219474		Sorting	Linear Garden (IOI08_linear_garden)	C++14	0 / 100	46 ms	65540 KiB

linear_garden

#include <bits/stdc++.h>

using namespace std;

const int kN = 1e6 + 3;

struct PairIntBool{
	bool second;
	int first;
	
	PairIntBool(){
		second = false;
	}
};

int n, m;
string garden;

PairIntBool dp[kN][1 << 5][5];
bool illegal[1 << 5];

int get_count(int pos, int mask, int diff){
	if(diff < 0 || diff > 4)
		return 0;
	mask |= 1 << diff;
	if(illegal[mask])
		return 0;
	if(pos == n)
		return 1;

	auto &[ans, solved] = dp[pos][mask][diff];
	if(solved)
		return ans;

	solved = true;
	ans = 0;

	ans += get_count(pos + 1, mask, diff + 1);
	ans += get_count(pos + 1, mask, diff - 1);
	while(ans >= m)
		ans -= m;

	return ans;
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(NULL);

	cin >> n >> m >> garden;

	for(int i = 1; i < (1 << 5); ++i){
		int min_bit, max_bit;
		for(int j = 0; j < 5; ++j){
			if((1 << j) & i){
				min_bit = j;
				break;
			}
		}
		for(int j = 4; j >= 0; --j){
			if((1 << j) & i){
				max_bit = j;
				break;
			}
		}

		if(max_bit - min_bit > 2)
			illegal[i] = true;
	}

	int ans = 1;
	int mask = (1 << 2), diff = 2;
	for(int i = 0; i < n; ++i){
		if(garden[i] == 'P'){
			ans += get_count(i + 1, mask, diff - 1);
			while(ans >= m)
				ans -= m;
		}
		if(garden[i] == 'L'){
			mask |= 1 << (diff - 1);
			diff -= 1;
		}
		else{
			mask |= 1 << (diff + 1);
			diff += 1;
		}
	}

	cout << ans << "\n";
}

Compilation message (stderr)

linear_garden.cpp: In function 'int get_count(int, int, int)':
linear_garden.cpp:31:8: warning: decomposition declaration only available with -std=c++1z or -std=gnu++1z
  auto &[ans, solved] = dp[pos][mask][diff];
        ^
linear_garden.cpp: In function 'int main()':
linear_garden.cpp:67:14: warning: 'max_bit' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(max_bit - min_bit > 2)
      ~~~~~~~~^~~~~~~~~
linear_garden.cpp:67:14: warning: 'min_bit' may be used uninitialized in this function [-Wmaybe-uninitialized]

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