Leetcode: Longest Common Prefix

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

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 String

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prefix equal the first string then compare to the next one. 

the prefix string will reduce its size each time when no common exist in next string. 

after going through all strings, the left prefix is the wanted one. 

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//code

       class Solution {

       public:

              string longestCommonPrefix(vector<string>& strs) {

                     string prefix;

                     //check input

                     if (strs.size() == 0)return prefix;

                     prefix = strs[0];

                     for (int i = 1; i<strs.size(); i++){

                           int j = 0, pSize = prefix.size();

                           for (; j<pSize; j++){

                                  if (j >= strs[i].size())break;

                                  if (prefix[j] != strs[i][j])break;

                           }

                           //delete the left chars in prefix

                           if (prefix[j] != prefix.size())prefix.erase(j, prefix.size() - j);

                     }

                     return prefix;

              }

       };