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Formatted question description: https://leetcode.ca/all/2427.html

2427. Number of Common Factors

  • Difficulty: Easy.
  • Related Topics: .
  • Similar Questions: Count Primes.

Problem

Given two positive integers a and b, return the number of **common factors of a and **b.

An integer x is a common factor of a and b if x divides both a and b.

  Example 1:

Input: a = 12, b = 6
Output: 4
Explanation: The common factors of 12 and 6 are 1, 2, 3, 6.

Example 2:

Input: a = 25, b = 30
Output: 2
Explanation: The common factors of 25 and 30 are 1, 5.

  Constraints:

  • 1 <= a, b <= 1000

Solution (Java, C++, Python)

  • class Solution {
        public int commonFactors(int a, int b) {
            int ans = 0, n = Math.min(a, b);
            for (int i = 1; i <= n; ++i) {
                if (a % i == 0 && b % i == 0) {
                    ++ans;
                }
            }
            return ans;
        }
    }
    
  • class Solution {
    public:
        int commonFactors(int a, int b) {
            int ans = 0;
            int n = min(a, b);
            for (int i = 1; i <= n; ++i) {
                if (a % i == 0 && b % i == 0) {
                    ++ans;
                }
            }
            return ans;
        }
    };
    
  • class Solution:
        def commonFactors(self, a: int, b: int) -> int:
            return sum(a % i == 0 and b % i == 0 for i in range(1, 1001))
    
    
  • func commonFactors(a int, b int) int {
    	ans := 0
    	for i := 1; i <= a && i <= b; i++ {
    		if a%i == 0 && b%i == 0 {
    			ans++
    		}
    	}
    	return ans
    }
    
  • function commonFactors(a: number, b: number): number {
        const n = Math.min(a, b);
        let ans = 0;
        for (let i = 1; i <= n; i++) {
            if (a % i == 0 && b % i == 0) ans += 1;
        }
        return ans;
    }
    
    

Explain:

nope.

Complexity:

  • Time complexity : O(n).
  • Space complexity : O(n).

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