From 21eb0e1c2fa8b9de34d4c6b4d3dee8b42e11347d Mon Sep 17 00:00:00 2001
From: caiwang-Z <58072883+caiwang-Z@users.noreply.github.com>
Date: Sun, 22 May 2022 19:12:06 +0200
Subject: [PATCH] Create binarySearch

---
 sortAlgorithm/binarySearch | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 sortAlgorithm/binarySearch

diff --git a/sortAlgorithm/binarySearch b/sortAlgorithm/binarySearch
new file mode 100644
index 0000000..fff28cf
--- /dev/null
+++ b/sortAlgorithm/binarySearch
@@ -0,0 +1,35 @@
+# 返回 x 在 arr 中的索引，如果不存在返回 -1
+def binarySearch (arr, l, r, x): 
+  
+    # 基本判断
+    if r >= l: 
+  
+        mid = int(l + (r - l)/2)
+  
+        # 元素整好的中间位置
+        if arr[mid] == x: 
+            return mid 
+          
+        # 元素小于中间位置的元素，只需要再比较左边的元素
+        elif arr[mid] > x: 
+            return binarySearch(arr, l, mid-1, x) 
+  
+        # 元素大于中间位置的元素，只需要再比较右边的元素
+        else: 
+            return binarySearch(arr, mid+1, r, x) 
+  
+    else: 
+        # 不存在
+        return -1
+  
+# 测试数组
+arr = [ 2, 3, 4, 10, 40 ] 
+x = 10
+  
+# 函数调用
+result = binarySearch(arr, 0, len(arr)-1, x) 
+  
+if result != -1: 
+    print ("元素在数组中的索引为 %d" % result )
+else: 
+    print ("元素不在数组中")