(Easy)1071. Greatest Common Divisor of Strings- LeetCode

Description:

For strings S and T, we say "T divides S" if and only if S = T + ... + T  (T concatenated with itself 1 or more times)

Return the largest string X such that X divides str1 and X divides str2.

 

Example 1:

Input: str1 = "ABCABC", str2 = "ABC"
Output: "ABC"

Example 2:

Input: str1 = "ABABAB", str2 = "ABAB"
Output: "AB"

Example 3:

Input: str1 = "LEET", str2 = "CODE"
Output: ""

 

Note:

1. 1 <= str1.length <= 1000
2. 1 <= str2.length <= 1000
3. str1[i] and str2[i] are English uppercase letters.

Accepted

12,036

Submissions

22,171

 

Solution:

First Attemp: Time Limit Exceeded.

 

 

 

class Solution {
    public String gcdOfStrings(String str1, String str2) {
     
       
        if(str1 ==null|| str2==null){
            return "";
        
        }
        int max = Integer.MIN_VALUE;
        String res="";
        for(int i = 0; i< str2.length(); i++){  
            for(int j = i; j<str2.length(); j++){
                //System.out.println(str2.substring(i,j+1));
               String tmp =  str2.substring(i,j+1);
                
                if(Find(str1,tmp)&&Find(str2, tmp)){
                    if(tmp.length()>max){
                        max = tmp.length();
                        res = tmp;
                    }
                }
            }
        }
        
        
        
        return res;
    }
    
    static boolean Find(String s1, String s2){
        
        int a = s1.length();
        int b = s2.length();
        int times = a/b;
        String s ="";
        if(s1.length()%s2.length()!=0){
            return false;
        }
        
        else{
            for(int i = 0; i<times; i++){
                s = s+ s2; 
            }    
            
        }
        
        if(s1.equals(s)){
            return true;
        }
        else{
            return false;
        }
    }
}

 

Second Attempt:

 

 

class Solution {
    public String gcdOfStrings(String str1, String str2) {
     
       
        if(str1 ==null|| str2==null){
            return "";
        
        }
        int max = Integer.MIN_VALUE;
        String res="";
        for(int i = 0; i< str2.length(); i++){  
        
                //System.out.println(str2.substring(0,i+1));
               String tmp =  str2.substring(0,i+1);
                
                if(Find(str1,tmp)&&Find(str2, tmp)){
                    if(tmp.length()>max){
                        max = tmp.length();
                        res = tmp;
                    }
                }
            
        }
        
        return res;
    }
    
    static boolean Find(String s1, String s2){
        
        int a = s1.length();
        int b = s2.length();
        int times = a/b;
        String s ="";
        if(s1.length()%s2.length()!=0){
            return false;
        }
        
        else{
            for(int i = 0; i<times; i++){
                s = s+ s2; 
            }    
            
        }
        
        if(s1.equals(s)){
            return true;
        }
        else{
            return false;
        }
    }
}