|
| 1 | +package com.leetcode_cn.easy; |
| 2 | +/***********稀疏数组搜索********/ |
| 3 | + |
| 4 | +/** |
| 5 | + * 稀疏数组搜索。有个排好序的字符串数组,其中散布着一些空字符串,编写一种方法,找出给定字符串的位置。 |
| 6 | + * |
| 7 | + * 示例1: |
| 8 | + * |
| 9 | + * 输入: words = ["at", "", "", "", "ball", "", "", "car", "", "","dad", "", ""], s = "ta" |
| 10 | + * 输出:-1 |
| 11 | + * 说明: 不存在返回-1。 |
| 12 | + * 示例2: |
| 13 | + * |
| 14 | + * 输入:words = ["at", "", "", "", "ball", "", "", "car", "", "","dad", "", ""], s = "ball" |
| 15 | + * 输出:4 |
| 16 | + * 提示: |
| 17 | + * |
| 18 | + * words的长度在[1, 1000000]之间 |
| 19 | + * |
| 20 | + */ |
| 21 | + public class SparseArraySearchLcci { |
| 22 | + |
| 23 | + public static void main(String[] args) { |
| 24 | + System.out.println(new SparseArraySearchLcci().findString(new String[]{"at", "", "", "", "ball", "", "", "car", "", "","dad", "", ""}, "ta")); |
| 25 | + } |
| 26 | + |
| 27 | + /** |
| 28 | + * 二分查找 |
| 29 | + * @param words |
| 30 | + * @param s |
| 31 | + * @return |
| 32 | + */ |
| 33 | + public int findString(String[] words, String s) { |
| 34 | + int start = 0; |
| 35 | + int end = words.length - 1; |
| 36 | + |
| 37 | + while(start <= end) { |
| 38 | + int mid = (start + end) / 2; |
| 39 | + int omid = mid; |
| 40 | + while(mid >= 0 && words[mid].length() == 0) { // 向左透过空串 |
| 41 | + mid--; |
| 42 | + } |
| 43 | + if (mid < 0) return -1; |
| 44 | + if (words[mid].compareTo(s) < 0) { |
| 45 | + start = omid + 1; // 如果在右边,使用初始mid |
| 46 | + } else if (words[mid].compareTo(s) > 0) { |
| 47 | + end = mid - 1; |
| 48 | + } else { |
| 49 | + return mid; |
| 50 | + } |
| 51 | + } |
| 52 | + return -1; |
| 53 | + } |
| 54 | +} |
0 commit comments