LeetCode14, the longest common prefix

Title description

Direct thinking

class Solution {
    
    
      public String longestCommonPrefix(String[] strs) {
    
    
            if(strs==null||strs.length<1){
    
    
                return "";
            }
             if(strs.length==1){
    
    
                return strs[0];
            }
            int start = 0;
            while(start<strs[0].length()) {
    
    
                for (int i = 1; i < strs.length; i++) {
    
    
                    if(start>=strs[i].length())/*aa，a的情况*/
                        return strs[0].substring(0, start);
                    if (strs[i].charAt(start) != strs[0].charAt(start))
                        return strs[0].substring(0, start);
                }
                start++;
            }

            return strs[0].substring(0,start);
    }
}

Complexity analysis:
Time complexity: O(mn), where m is the average length of the strings in the string array, and n is the number of strings. In the worst case, each character of each string in the string array will be compared once.

Space complexity: O(1). The extra space complexity used is constant.

Strange submission result:

Precautions:

• 1. Boundary issues
• 2. Array out of bounds problem