Submission #42391

#	Time	Username	Problem	Language	Result	Execution time	Memory
42391		RezwanArefin01	Snake Escaping (JOI18_snake_escaping)	C++14	0 / 100	488 ms	65536 KiB

snake_escaping

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> ii; 

ll dp[1 << 20], dp2[1 << 20], ans; 
char b[1 << 20], s[1 << 20];
int l, q;

void recurr1(int i, int num, int tot) {
	if(i == l) {
		if(tot & 1) ans -= dp[num];
		else ans += dp[num];
		return; 
	}
	if(s[i] == '0') recurr1(++i, num << 1, tot); 
	else if(s[i] == '?') recurr1(++i, num << 1 | 1, tot);
	else {
		recurr1(++i, num << 1 | 1, tot); 
		recurr1(++i, num << 1, ++tot);
	}
}

void recurr0(int i, int num, int tot) {
	if(i == l) {
		if(tot & 1) ans -= dp2[num];
		else ans += dp2[num];
		return; 
	}
	if(s[i] == '1') recurr0(++i, num << 1 | 1, tot);
	else if(s[i] == '?') recurr0(++i, num << 1, tot);
	else {
		recurr0(++i, num << 1, tot);
		recurr0(++i, num << 1 | 1, ++tot);
	}
}
void recurrw0t(int i, int num) {
	if(i == l) {
		ans += b[num] - '0';
		return;
	} 
	if(s[i] == '?') {
		recurrw0t(++i, num << 1 | 1);
		recurrw0t(++i, num << 1);
	} else recurrw0t(++i, (num << 1) + (s[i] == '1'));
}

int main(int argc, char const *argv[]) {
#ifdef LOCAL_TESTING
	freopen("in", "r", stdin);
#endif
	scanf("%d %d", &l, &q);
	scanf(" %s", b);

	for(int i = 0; i < (1 << l); ++i) 
		dp[i] = dp2[i] = b[i] - '0';
	
	for(int i = 0; i < l; ++i) 
		for(int j = 0; j < (1 << l); ++j) 
			if(j >> i & 1) dp[j] += dp[j ^ (1 << i)];

	for(int i = 0; i < l; ++i) 
		for(int j = 0; j < (1 << l); ++j) 
			if(~j >> i & 1) dp2[j] += dp2[j | (1 << i)];

	while(q--) {
		scanf(" %s", s);
		int n0 = 0, n1 = 0, nw0t = 0; 
		for(int i = 0; i < l; ++i) {
			n0 += s[i] == '0';
			n1 += s[i] == '1';
			nw0t += s[i] == '?';
		}

		if(n1 == 0) {
			int num = 0;
			for(int i = 0; i < l; ++i) 
				num = (num << 1) + (s[i] == '?');
			printf("%lld\n", dp[num]);
		} else if(nw0t == 0) {
			int num = 0;
			for(int i = 0; i < l; ++i) 
				num = (num << 1) + (s[i] == '1');
			printf("%c\n", b[num]);
		} else {
			ans = 0;
			if(nw0t <= n1 && nw0t <= n0) recurrw0t(0, 0);
			else if(n1 <= nw0t && n1 <= n0) recurr1(0, 0, 0);
			else recurr0(0, 0, 0);
			printf("%lld\n", ans);
		}
	}
}

Compilation message (stderr)

snake_escaping.cpp: In function 'void recurrw0t(int, int)':
snake_escaping.cpp:46:51: warning: operation on 'i' may be undefined [-Wsequence-point]
  } else recurrw0t(++i, (num << 1) + (s[i] == '1'));
                                                   ^
snake_escaping.cpp: In function 'int main(int, const char**)':
snake_escaping.cpp:53:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &l, &q);
                        ^
snake_escaping.cpp:54:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf(" %s", b);
                 ^
snake_escaping.cpp:68:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf(" %s", s);
                  ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 10
• Subtask 4: 0 / 53
• Subtask 5: 0 / 25