367. Valid Perfect Square

Problem

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Difficulty: Easy
Tags: Math, Binary Search

Intuition

this one seemed easy. i can just compare the number with all the perfect squres and finds it. it will only take sqrt(n) time.

Approach

just compare the num with all the perfect squares from 1 to max.

Solution

bool isPerfectSquare(int num) {
    int i, k;
    i = 1;
    k = 1;
    while(true){
        if(num == k){
            return true;
        }
        i++;
        if(i > 46340){
            return false;
        }
        k = i*i;
        if(k > num){
            return false;
        }
    }
}

Complexity

• Time: $O(\sqrt n)$

• Space: $O(1)$

Thoughts

this one was easy.