Longest Common Prefix

Problem

Write a function to find the longest common prefix string amongst an array of strings.
If there is no common prefix, return an empty string “”.

Example

Input: strs = ["flower","flow","flight"]
Output: "fl"

Input: strs = ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Constraints

• 1 <= strs.length <= 200
• 0 <= strs[i].length <= 200
• strs[i] consists of only lower-case English letters.

Solution

/**
 * @param {string[]} strs
 * @return {string}
 */
var longestCommonPrefix = function (strs) {
    if (strs.length === 1) {
        return strs[0];
    }
    var commonStr = strs[0];

    for (let i = 1; i < strs.length; i++) {
        var lastIndex = commonStr.length;
        for (let ii = 0; ii < commonStr.length && ii < strs[i].length; ii++) {
            if (commonStr[ii] !== strs[i][ii]) {
                lastIndex = ii;
                break;
            }
        }
        if (lastIndex >= strs[i].length) {
            lastIndex = strs[i].length;
        }
        commonStr = commonStr.slice(0, lastIndex);
    }
    return commonStr;
};