14. 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 1:

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

Example 2:

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

Note:

All given inputs are in lowercase letters a-z.

Solution:

ONE

JavaScript specific solution. Get the min len then narrow down the prefix.

///**
 * @param {string[]} strs
 * @return {string}
 */let longestCommonPrefix = function (strs) {if (strs.length > 0) {let minLen = Math.min(...strs.map((s) => s.length));const anyStr = strs[0];while (minLen) {const prefix = anyStr.slice(0, minLen--);if (strs.every((s) => s.startsWith(prefix))) {return prefix;}}}return '';};

TWO

///**
 * @param {string[]} strs
 * @return {string}
 */let longestCommonPrefix = function (strs) {if (strs.length <= 0) {return '';}let i = 0;while (strs.every((s) => s[i] && s[i] === strs[0][i])) {
        i++;}return strs[0].slice(0, i);};

THREE

General solution. Build up the prefix.

///**
 * @param {string[]} strs
 * @return {string}
 */let longestCommonPrefix = function (strs) {let prefix = '';if (strs.length > 0) {for (let i = 0; ; i++) {const c = strs[0][i];if (!c) {return prefix;}for (let j = 0; j < strs.length; j++) {if (strs[j][i] !== c) {return prefix;}}
            prefix += c;}}return prefix;};

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