LeetCode:Longest Common Prefix

Longest Common Prefix

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

Solution：

public class Solution {
    public String longestCommonPrefix(String[] strs) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int n = strs.length;
        if(n==0) return "";
        int i=0;
        for(i=0;i<strs[0].length();i++){
            char c = strs[0].charAt(i);
            for(int j=1;j<strs.length;j++){
                if(i>=strs[j].length() || strs[j].charAt(i)!=c) return strs[0].substring(0,i);
            }
        }
        return strs[0].substring(0,i);
    }
}

 以字符串个数作为外循环

class Solution {
public:
    string longestCommonPrefix(vector<string> &strs) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
     if (strs.size() == 0) {
         return "";
     }
     int longest_common_prefix_len = strs[0].size();
     for (int i = 1; i < strs.size(); ++i) {
         for (int j = 0; j < longest_common_prefix_len; ++j) {
             if (strs[i][j] != strs[0][j]) {
                 longest_common_prefix_len = j;
             }
         }
     }
     return strs[0].substr(0,longest_common_prefix_len);
    }
};