704.Binary Search.

Author: recherst

Easy/704.Binary Search.playground/Contents.swift

@@ -0,0 +1,45 @@
+/**
+ Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.
+
+ You must write an algorithm with O(log n) runtime complexity.
+
+  
+
+ Example 1:
+ Input: nums = [-1,0,3,5,9,12], target = 9
+ Output: 4
+ Explanation: 9 exists in nums and its index is 4
+ 
+ Example 2:
+ Input: nums = [-1,0,3,5,9,12], target = 2
+ Output: -1
+ Explanation: 2 does not exist in nums so return -1
+  
+
+ Constraints:
+ - 1 <= nums.length <= 104
+ - -104 < nums[i], target < 104
+ - All the integers in nums are unique.
+ - nums is sorted in ascending order.
+ */
+class Solution {
+    func search(_ nums: [Int], _ target: Int) -> Int {
+        var left = 0
+        var right = nums.count - 1
+        while left <= right {
+            var middle = (left + right) / 2
+            if nums[middle] == target {
+                return middle
+            } else if nums[middle] > target {
+                right = middle - 1
+            } else {
+                left = middle + 1
+            }
+        }
+        return -1
+    }
+}
+
+let s = Solution()
+let r = s.search([5], 5)
+print(r)

Easy/704.Binary Search.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Easy/704.Binary Search.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -127,6 +127,7 @@
 123. [Count Binary Substrings](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/696.Count%20Binary%20Substrings.playground/Contents.swift)
 124. [Degree of an Array](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/697.Degree%20of%20an%20Array.playground/Contents.swift)
 125. [Long Pressed Name](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/925.Long%20Pressed%20Name.playground/Contents.swift)
+126. [Binary Search](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/704.Binary%20Search.playground/Contents.swift)
 
 #### Medium