chore(Python): added ternary_search (#274)

algorithms/Python/README.md

@@ -17,6 +17,7 @@
 1. [Binary Search](searching/binary_search.py)
 2. [Jump Search](searching/jump_search.py)
 3. [Linear Search](searching/linear_search.py)
+4. [Ternary Search](searching/ternary_search.py)
  
 ## Sorting
 1. [Bubble Sort](sorting/bubble_sort.py)

algorithms/Python/searching/ternary_search.py

@@ -0,0 +1,47 @@
+"""
+    TERNARY SEARCH
+    Time Complexity: O(log3 N)
+    Working: Similar to binary search but here we have two searc point (mid)
+    Steps:
+        1. Compare with elements at mid1 and mid2. Stop if found
+        2. If more than mid1 and less than mid2 - working field is the second part
+        3. If less than mid1 - working field is the first part
+        4. If more than mid2 - working field is the third part
+"""
+arr = [10, 13, 46, 51, 139, 467]
+targets = [2, 467]
+
+def ternarySearch(arr, target):
+    left, right = 0, len(arr) - 1
+    index = -1
+
+    while(left <= right):
+        mid1, mid2 = left + (right - left) // 3, right - (right - left) // 3
+
+        # checking for condition 1
+        if target == arr[mid1]:
+            index = mid1
+            break
+        if target == arr[mid2]:
+            index = mid2
+            break
+
+        # checking for condition 2
+        if target > arr[mid1] and target < arr[mid2]:
+            left, right = mid1 + 1, mid2 - 1
+
+        # checking for condition 3
+        elif target < arr[mid1]:
+            right = mid1 - 1
+
+        # checking for condition 4
+        else:
+            left = mid2 + 1
+    return index
+
+for target in targets:
+    result = ternarySearch(arr, target)
+    if result == -1:
+        print(target, "is not present in", arr)
+    else:
+        print(target, "is present in the position:", result + 1)