文章目录
代码随想录
主要题目
344. 反转字符串
https://leetcode.cn/problems/reverse-string/description/
var reverseString = function(s) {
for(let i=0,j=s.length-1;i<j;i++,j--){
[s[i],s[j]]=[s[j],s[i]]
}
};
541. 反转字符串 II
https://leetcode.cn/problems/reverse-string-ii/description/
注意：
- js的字符串是常量，是不能在字符串上修改的
- 因此这里要把字符串拆成数组，
s.split - 最后再把数组拼回字符串，
s.join
/**
* @param {string} s
* @param {number} k
* @return {string}
*/
var reverseStr = function (s, k) {
const len = s.length;
let arr = s.split('');
for (let i = 0; i < len; i += 2 * k) {
let l = i, r = l + k - 1 > len - 1 ? len - 1 : l + k - 1;
while (l < r) {
[arr[l], arr[r]] = [arr[r], arr[l]]
l++, r--
}
}
return arr.join('');
};
剑指 Offer 05. 替换空格
https://leetcode.cn/problems/ti-huan-kong-ge-lcof/description/
/**
* @param {string} s
* @return {string}
*/
var replaceSpace = function (s) {
let num = 0;
let arr = [];
for (let i = 0; i < s.length; i++) {
if (s[i] == ' ') arr.push('%20')
else arr.push(s[i])
}
return arr.join('');
};
151. 反转字符串中的单词
https://leetcode.cn/problems/reverse-words-in-a-string/
注意：会有多个空格，而字符串中的空格在split后为''
/**
* @param {string} s
* @return {string}
*/
// 在数组中去除多余空格
var space = function (arr) {
let arr1 = []
for (let i = 0; i < arr.length; i++) {
if (arr[i] != '') {
arr1.push(arr[i])
}
}
return arr1;
}
var reverseWords = function (s) {
let arr = s.split(' ');
let arr1 = space(arr)
for (let i = 0, j = arr1.length - 1; i < j; i++, j--) {
[arr1[i], arr1[j]] = [arr1[j], arr1[i]]
}
return arr1.join(" ")
};
剑指 Offer 58 - II. 左旋转字符串
https://leetcode.cn/problems/zuo-xuan-zhuan-zi-fu-chuan-lcof/description/
var reverseLeftWords = function (s, n) {
for (let i = 0; i < n; i++) {
s += s[i]
}
return s.slice(n);
};
28. 找出字符串中第一个匹配项的下标（KMP）还没写
https://leetcode.cn/problems/find-the-index-of-the-first-occurrence-in-a-string/