算法-数据结构

描述/** * 翻转指定字符串中的内容,每个单词以空格字符分开 * * input： "the sky is blue" * * output: "blue is sky the" */既有APIfun reversStringByCollection(s: String): String { // 分割 val str: MutableList<String> = s.split("\\s+".toRegex()) as MutableList<String> // 翻转 str.reverse() // 插入 return str.joinToString(separator = " ")}双指针fun reversStringByPointer(s: String): String { // 定义左右指针，右指针不动，左指针向左移动取单词 var right = s.length - 1 var left = right // 存放翻转后的字符 val sb = StringBuilder() while (left >= 0) { // 查找第一次出现的空格 while (left >= 0 && s[left] != ' ') left-- sb.append(s.substring(left + 1, right + 1) + " ") while (left >= 0 && s[left] == ' ') left-- // 右指针移动 right = left } return sb.toString().trimEnd()}双端队列fun reversStringByQueue(s: String):String { var left = 0 // 构建双端队列 val deque: Deque<String> = ArrayDeque() val sb = StringBuilder() while (left <= s.length - 1) { if (s.isNotEmpty() && s[left] == ' ') { // 将单词push到队列头部 deque.offerFirst(sb.toString()) // sb.setLength(0) } else if (s[left] != ' ') { sb.append(s[left]) } // 移动指针 ++left } // 插入最后一个单词 deque.offerFirst(sb.toString()) return (deque.toTypedArray() as Array<String> ).joinToString(separator = " ")}