Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.

 

public class Solution {
    public String longestCommonPrefix(String[] strs) {
        String compare ="";
        if(strs.length == 0)
            return compare;
        
        compare = strs[0];
        for(int i = 1; i < strs.length; i++){
            int j = 0;
            while(j < compare.length() && j < strs[i].length()){
                if(compare.charAt(j) != strs[i].charAt(j)){
                    break;
                }
                j++;
            }
            compare = strs[i].substring(0,j);
        }
        return compare;
    }
}

方法二： ref:http://www.cnblogs.com/feiling/p/3159771.html

依次比较每个字符串的相应位置的字符，直到遇到不匹配项。可以减少不必要的比较

public class Solution {
    public String longestCommonPrefix(String[] strs) {
         String compare = "";
         if(strs.length == 0)
             return compare;
         
         int k = 0;
         while(true){
             char p = ' '; 
             int i;
             for(i = 0; i < strs.length; i++){
                if(k == strs[i].length())
                    break;
                     
                if(i == 0)
                    p = strs[i].charAt(k);
                
                 if(p != strs[i].charAt(k))
                     break;
             }
             
             // 出for循环后，检查是循环结束还是break跳出的循环
             // 如果是break跳出的循环，就break跳出while
             if(i != strs.length)
                 break;
             
             compare += p;
             k++;
         }
         
         return compare;
     }
}