{"id":3089,"date":"2018-07-12T08:18:21","date_gmt":"2018-07-12T15:18:21","guid":{"rendered":"http:\/\/zxi.mytechroad.com\/blog\/?p=3089"},"modified":"2018-07-12T08:18:32","modified_gmt":"2018-07-12T15:18:32","slug":"leetcode-704-binary-search","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/algorithms\/array\/leetcode-704-binary-search\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 704. Binary Search"},"content":{"rendered":"<h1><strong>Problem<\/strong><\/h1>\n<p>Given a\u00a0<strong>sorted<\/strong>\u00a0(in ascending order) integer array\u00a0<code>nums<\/code>\u00a0of\u00a0<code>n<\/code>\u00a0elements and a\u00a0<code>target<\/code>\u00a0value, write a function to search\u00a0<code>target<\/code>\u00a0in\u00a0<code>nums<\/code>. If\u00a0<code>target<\/code>\u00a0exists, then return its index, otherwise return\u00a0<code>-1<\/code>.<\/p>\n<p><strong>Example 1:<\/strong><\/p>\n<pre class=\"crayon:false\"><strong>Input:<\/strong> <code>nums<\/code> = [-1,0,3,5,9,12], <code>target<\/code> = 9 <strong>Output:<\/strong> 4 <strong>Explanation:<\/strong> 9 exists in <code>nums<\/code> and its index is 4<\/pre>\n<p><strong>Example 2:<\/strong><\/p>\n<pre class=\"crayon:false\"><strong>Input:<\/strong> <code>nums<\/code> = [-1,0,3,5,9,12], <code>target<\/code> = 2 <strong>Output:<\/strong> -1 <strong>Explanation:<\/strong> 2 does not exist in <code>nums<\/code> so return -1<\/pre>\n<p>&nbsp;<\/p>\n<p><strong>Note:<\/strong><\/p>\n<ol>\n<li>You may assume that all elements in\u00a0<code>nums<\/code>\u00a0are unique.<\/li>\n<li><code>n<\/code>\u00a0will be in the range\u00a0<code>[1, 10000]<\/code>.<\/li>\n<li>The value of each element in\u00a0<code>nums<\/code>\u00a0will be in the range\u00a0<code>[-9999, 9999]<\/code>.<\/li>\n<\/ol>\n<h1><strong>Solution: Binary Search<\/strong><\/h1>\n<p>Time complexity: O(logn)<\/p>\n<p>Space complexity: O(1)<\/p>\n<pre class=\"lang:c++ decode:true\">\/\/ Author: Huahua\r\n\/\/ Running time: 32 ms\r\nclass Solution {\r\npublic:\r\n  int search(vector&lt;int&gt;&amp; nums, int target) {\r\n    int l = 0;\r\n    int r = nums.size();\r\n    while (l &lt; r) {\r\n      int m = (r - l) \/ 2 + l;\r\n      if (nums[m] == target) \r\n        return m;\r\n      else if (nums[m] &gt; target)\r\n        r = m;\r\n      else\r\n        l = m + 1;\r\n    }\r\n    return -1;\r\n  }\r\n};<\/pre>\n<p>STL<\/p>\n<pre class=\"lang:default decode:true \">\/\/ Author: Huahua\r\n\/\/ Running time: 36 ms\r\nclass Solution {\r\npublic:\r\n  int search(vector&lt;int&gt;&amp; nums, int target) {\r\n    auto it = lower_bound(nums.begin(), nums.end(), target);\r\n    if (it == nums.end() || *it != target) return -1;\r\n    return it - nums.begin();\r\n  }\r\n};<\/pre>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Problem Given a\u00a0sorted\u00a0(in ascending order) integer array\u00a0nums\u00a0of\u00a0n\u00a0elements and a\u00a0target\u00a0value, write a function to search\u00a0target\u00a0in\u00a0nums. If\u00a0target\u00a0exists, then return its index, otherwise return\u00a0-1. Example 1: Input: nums&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[184],"tags":[52,222],"class_list":["post-3089","post","type-post","status-publish","format-standard","hentry","category-array","tag-binary-search","tag-easy","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/3089","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/comments?post=3089"}],"version-history":[{"count":2,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/3089\/revisions"}],"predecessor-version":[{"id":3091,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/3089\/revisions\/3091"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=3089"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=3089"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=3089"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}