14.Longest Common Prefix

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

Analyse:

找出陣列所有string中最長的共同prefix.

依序兩兩相比並記錄prefix.

Solution:

class Solution {

    func longestCommonPrefix(_ strs: [String]) -> String {
       if(strs.count == 0) {
           return "";
       }

       var output = strs[0];

       for i in 1..<strs.count {
           output = findCommonPrefix(output, strs[i]);
       }

       return output;
    }

    func findCommonPrefix(_ str1: String, _ str2: String) -> String {
        let chars1 = Array(str1)
        let chars2 = Array(str2)
        var output = "";

        var i = 0;

        while(i < chars1.count && i < chars2.count && chars1[i] == chars2[i]) {
            output = output + String(chars1[i]);
            i += 1;
        }

        return output;  
    }
}