Binary-Search-1

problem1.py

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+# https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size/
+# Time Complexity O(log(m*n)) m*n elements
+# Space Complexity O(1)
+
+
+class Solution:
+    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
+        m = len(matrix)  # rows [[],[],[]]
+        n = len(matrix[0])  # columns
+        low = 0
+        high = (m * n) - 1
+        while low <= high:
+            mid = (low + high) // 2
+            r = mid // n
+            c = mid % n
+            if matrix[r][c] == target:
+                return True
+            if matrix[r][c] < target:
+                low = mid + 1
+            else:
+                high = mid - 1
+        return False

problem2.py

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+# https://leetcode.com/problems/search-in-rotated-sorted-array/
+# Time Complexity O(log(n))
+# Space Complexity O(1)
+
+
+class Solution:
+    def search(self, nums: List[int], target: int) -> int:
+        low = 0
+        high = len(nums) - 1
+        while low <= high:
+            mid = (low + high) // 2
+            if nums[mid] == target:
+                return mid
+            # left sorted
+            if nums[low] <= nums[mid]:
+                # nums[low] <= target < nums[mid] indicates target could be in the left half
+                if nums[low] <= target < nums[mid]:
+                    high = mid - 1
+                else:
+                    low = mid + 1
+            # right sorted
+            else:
+                if nums[mid] < target <= nums[high]:
+                    low = mid + 1
+                else:
+                    high = mid - 1
+        return -1

problem3.py

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+# https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size/
+# Time Complexity O(log(n)) here both loops have same range so it wont be m+n
+# Space Complexity O(1)
+
+
+class Solution:
+    def search(self, reader: "ArrayReader", target: int) -> int:
+        low, high = 0, 1
+        while reader.get(high) < target:
+            high *= 2
+
+        while low <= high:
+            mid = (low + high) // 2
+            if reader.get(mid) == target:
+                return mid
+            if reader.get(mid) > target:
+                high = mid - 1
+            else:
+                low = mid + 1
+        return -1