leetcode: Longest Common Prefix

http://oj.leetcode.com/problems/longest-common-prefix/

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

思路：

没什么技巧，第一行第一个字符拿出来和其它所有行的第一个字符比，然后第二个，第三个。如果碰到不相等或某行结束就中断。

class Solution {
public:
    string longestCommonPrefix(vector<string> &strs) {
        if (0 == strs.size()) {
            return string();
        }
        
        int i = 0;
        bool stop = false;
        
        while (!stop) {
            char ch = '';
            vector<string>::const_iterator it;
            
            for (it = strs.begin(); it != strs.end(); ++it) {
                if (i < it->length()) {
                    if ('' == ch) {
                        ch = (*it)[i];
                    }
                    else {
                        if (ch != (*it)[i]) {
                            stop = true;
                            break;
                        }
                    }
                }
                else {
                    stop = true;
                    break;
                }
            }
            
            ++i;
        }
        
        return strs[0].substr(0, i - 1);
    }
};