EOEO - Editorial

editorial
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22

Can anyone help me with this. Got WA for subtask-2 for my solution:
https://www.codechef.com/viewsolution/34236993

23

Someone explain me whats wrong with my solution CodeChef: Practical coding for everyone

24

thanks for formatting it doe :+1:

25

yeah the logic is sound…
what was the result?

26

i tried running your code on online IDE but its giving EOF error dunno why
my approach:
t = int(input())
for i in range(t):
…ts = int(input())
…if ts % 2 == 0:
…while(ts % 2 == 0):
… ts = ts // 2
…j = (ts - 1) // 2
…else:
…j = (ts - 1) // 2
print(j)

27

upd : for PYTH 3.6, use N//2 instead of int(N/2) or (N-1)/2

28

What a bad explanation

1 Like
29

video Explanation>>>

30

AC, both subtasks.

31

I did it using a different approach i solved the subtasks having considering three cases : first if the number (ts) is odd then answer will be floor(ts/2) and if the number (ts) is even then the number will either be a power of two or not a power of two . If the number is a power of two then the answer is 0 otherwise if the number is not a power of two then we simply divide the number until the number becomes odd and when the number becomes odd the answer will (ts)/2 as it was done in case 1.

Solution Link: CodeChef: Practical coding for everyone

32

Python 3.6

TS = TS/2 (i)

using above statement gives zero in subtask2 that is original constraints (1≤T≤10^5* 1≤TS≤10^18)

but if you use
TS = TS//2 (ii)
it passes with 100% score.

Because in (ii) you are storing TS as integer while in (i) its float which requires more memory in storage.

33

Hi ,
Can anyone help me with this .
what am I doing wrong , it is giving TLE for 2nd test case when I am using floor Function and same logic without floor is getting accepted.
https://www.codechef.com/viewsolution/34468313

34

for _ in range(int(input())):
ts=int(input())

if ts%2==0:
    while(ts%2!=1):
        ts=ts/2

if ts%2!=0:
print(int(ts//2))

Can anyone suggest what is wrong in this implementation ?? Logic is exactly same but 2nd test case is not passing while submitting. Any help is appreciated. Thank you.

35

To find 2^i we can also do (TS & -TS) right? So it’s O(1) per test case?

36

I cant debug with my solution can anyone help me?
https://www.codechef.com/viewsolution/34374913

37

Same issue bro i have also used this same approach

39

We can do it in one line : O(1)

Answer: TS / ((TS & ( (~TS) + 1)) << 1);
where TS is input, Tom Strength

41

any corner cases in the question

42

No

43

I am getting TLE , can anyone help me to optimize my code.

import java.util.ArrayList;
import java.util.Scanner;

public class ChefAndStrings {

public static void main(String[] args) {
	Scanner s = new Scanner(System.in);
	int t = s.nextInt();

	for (int i = 0; i < t; i++) {
		int c = 0, evan_c = 0;

		ArrayList<Integer> arr = new ArrayList<>();
		int ts = s.nextInt();

		for (int j = 2; j < ts; j++) {
			if (j % 2 == 0) {
				arr.add(j);
				c++;
			}
		}
		if (ts % 2 != 0) {
			System.out.println(c);
		} else {
			while (ts % 2 == 0 || ts > 0) {
				ts /= 2;
			}
			if (ts == 0) {
				System.out.println(0);
			} else {
				for (int k = 0; k < arr.size(); k++) {
					if (arr.get(k) / 2 < ts && arr.get(k) % 2 == 0)
						evan_c++;
				}
				System.out.println(evan_c);
			}
		}

	}
}

}