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`.
```
var longestCommonPrefix = function(strs) {
if(!strs.length) return '';
var len = strs.reduce((pre,item)=>{
return Math.min(pre,item.length);
},Number.MAX_VALUE);
var ans='';
for(var i=0;i<len;i++){
var a = strs[0][i];
var f = strs.every((item)=>{
return item[i] === a;
});
if(!f) break;
ans += a;
}
return ans;
};
```
```
var longestCommonPrefix = function(strs) {
if (!strs.length) return ""
let baseWord = strs[0];
for (let word = 1; word < strs.length; word++) {
// currWord = String(strs[word])
while (String(strs[word]).indexOf(baseWord) !== 0 && baseWord !== "") {
baseWord = baseWord.substring(0, baseWord.length - 1)
}
}
return baseWord;
};
```
```
var longestCommonPrefix = function(strs) {
if (strs.length == 0) return "";
let prefix = strs[0];
for (let i = 1; i < strs.length; i++)
while (strs[i].indexOf(prefix) != 0) {
prefix = prefix.slice(0, prefix.length - 1);
if (prefix==="") return "";
}
return prefix;
};
```
reduce() 方法接收一個函數作為累加器(accumulator),數組中的每個值(從左到右)開始縮減,最終為一個值。
reduce() 為數組中的每一個元素依次執行回調函數,不包括數組中被刪除或從未被賦值的元素,接受四個參數:初始值(或者上次回調函數的返回值),當前元素值,當前索引,調用reduce的數組。
```
arr.reduce(callback, [initialValue])
```
callback (執行數組中每個值的函數,包含四個參數)
- previousValue (上一次調用回調返回的值,或者是提供的初始值(initialValue))
- currentValue (數組中當前被處理的元素)
- index (當前元素在數組中的索引)
- array (調用 reduce 的數組)
initialValue (作為第一次調用 callback 的第一個參數)
```
var arr = [1, 2, 3, 4];
var sum = arr.reduce(function(pre, cur, index, arr) {
console.log(pre, cur, index);
return pre + cur;
})
console.log(arr, sum);
```

- 說明
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- Leetcode JAVA實現
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- leetcode232. Implement Queue using Stacks
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- leetcode237. Delete Node in a Linked List
- leetcode242. Valid Anagram
- leetcode258. Add Digits
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- leetcode292. Nim Game
- leetcode344. Reverse String
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- Leetcode JS 實現
- Js-leetcode 1. Two Sum
- Js-leetcode 2. Add Two Numbers
- Js-leetcode 10. Regular Expression Matching
- Js-leetcode 14. Longest Common Prefix
- Js-leetcode 17.Letter Combinations of a Phone Number
- Js-leetcode 20. Valid Parentheses
- Js-leetcode 27. Remove Element
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- Js-leetcode 136. Single Number
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- Js-leetcode 189. Rotate Array
- Js-leetcode 215. Kth Largest Element in an Array
- Js-leetcode 217. Contains Duplicate
- Js-leetcode 258. Add Digits
- Js-leetcode 263.Ugly Number
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- document
- 劉宇波老師--基礎知識
- 算法與數據結構
- 數據機構與算法介紹
- 二叉樹
- 堆
- 鏈表
- 隊列
- 并查集
- 最小生成樹
- 圖論
- 最短路徑
- 總結
- 玩轉數據結構
- 介紹
- 數組
- 棧和隊列
- 玩轉鏈表
- 鏈表與遞歸
- 二分搜索樹
- 集合與映射
- 第8章 優先隊列和堆
- 第9章 線段樹
- 第10章 Trie
- 玩轉算法面試 leetcode題庫分門別類詳細解析
- 第一章 介紹
- 第二章 時間復雜度和空間復雜度
- 第三章
- 深度實戰玩轉算法
- JS數據結構與算法
- 第一章.介紹
- 第二章.字符串
- 第三章.數組
- 第四章
- 第五章.排序
- 第六章.遞歸
- 第七章.棧
- 第八章.隊列
- 第九章.鏈表
- 第十章.矩陣
- 第十一章.二叉樹
- 第十二章.堆
- 極客時間
- 第01課丨數據結構與算法總覽
- 第02課丨訓練準備和復雜度分析
- 第03課丨數組、鏈表、跳表
- 第04課丨棧、隊列、優先隊列、雙端隊列
- 算法基礎
- 哈希表(散列表)
- 異或運算
- leetcode
- KD樹(K-Dimension Tree)
- Rtree
- B站-左神
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- 1 認識復雜度、對數器、二分法與異或運算
- 2 鏈表結構、棧、隊列、遞歸行為、哈希表和有序表
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