hw

search.py

@@ -19,3 +19,58 @@
 Output: 0
 Explanation: -1 exists in the list and its index is 0
 """
+
+# distance = high index - low index
+# middle index = low index + (distance // 2)
+
+def binary_search(nums, target):
+    # keep track of the window -- start by assuming the entire list is the window
+    # vars for low index of the window, high index of the window, middle point index of the window
+    low = 0
+    high = len(nums)
+    mid = high // 2
+
+    # continuously iterate until target is found or we determine that the target cannot be found
+    while True:
+        # check the value at the midpoint against the target, stop iterating if target is found
+        if nums[mid] == target:
+            return mid
+
+        # if the value at midpoint is less that the tartget, slide the window left
+        elif nums[mid] > target:
+            high = mid
+            difference = high - low
+            mid = low + (difference // 2)
+
+        else:
+            low = middifference = high - low
+            mid = low + (difference // 2)
+        # stop iteration when the midpoint is equal to low or high, because we did not find it
+        if mid <= low or mid >= high:
+            return -1
+
+        nums = [-1, 0, 3, 5, 9, 12]
+        target = 2
+        print(binary_search(nums, target))
+
+
+# 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
+
+# Example 3:
+# Input: nums = [-1, 0, 3, 5, 9, 12], target = 12
+# Output: 5
+# Explanation: 12 exists in the list and its index is 5
+
+# Example 4:
+# Input: nums = [-1, 0, 3, 5, 9, 12], target = -1
+# Output: 0
+# Explanation: -1 exists in the list and its index is 0
+# """