Determine two elements from the array whose sum is equal to specified sum

Author: OmkarPathak

Arrays/P05_CheckForPairSum.py

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+# Author: OMKAR PATHAK
+
+# Given an array A[] of n numbers and another number x, determines whether or not there exist two elements
+# in S whose sum is exactly x.
+
+def checkSum(array, sum):
+    # sort the array in descending order
+    array = quickSort(array)
+
+    leftIndex = 0
+    rightIndex = len(array) - 1
+
+    while leftIndex < rightIndex:
+        if (array[leftIndex] + array[rightIndex] ==  sum):
+            return array[leftIndex], array[rightIndex]
+        elif(array[leftIndex] + array[rightIndex] < sum):
+            leftIndex += 1
+        else:
+            rightIndex += 1
+
+    return False, False
+
+def quickSort(array):
+    if len(array) <= 1:
+        return array
+    pivot = array[len(array) // 2]
+    left = [x for x in array if x < pivot]
+    middle = [x for x in array if x == pivot]
+    right = [x for x in array if x > pivot]
+    return quickSort(left) + middle + quickSort(right)
+
+if __name__ == '__main__':
+    myArray = [10, 20, 30, 40, 50]
+    sum = 80
+
+    number1, number2 = checkSum(myArray, sum)
+    if(number1 and number2):
+        print('Array has elements:', number1, 'and', number2, 'with sum:', sum)
+    else:
+        print('Array doesn\'t has elements with the sum:', sum)