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Welcome to

This is going to be a website contains mainly educational resources.

Why the name of return0

In Linux/Unix environment, when a program exits with a return code 0, it indicates the program successfully exits.

What to expect?

Return0 will provide both fundamental computer science concept, in format of crash course and detailed explaination, programming challenges and more.

Sample leetcode question: Given two integers a and b, return the sum of the two integers without using the operators + and -.

def getSum(self, a: int, b: int) -> int:
    x, y = abs(a), abs(b)
    if x < y:
        return self.getSum(b, a)  
    sign = 1 if a > 0 else -1

    if a * b >= 0:
        while y:
            x, y = x ^ y, (x & y) << 1
        while y:
            x, y = x ^ y, ((~x) & y) << 1

    return x * sign

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