added question description to array datastructure index.md

owais4321 · owais4321 · commit 38889cf10bda · 2020-03-20T03:45:12.000-07:00
diff --git a/data_structures/array/index.md b/data_structures/array/index.md
@@ -1,34 +1,122 @@
 # Index of array
 
 * [Permumations of Word](permutations_of_word.py)
+
+Find Permuatation of a given word. 
 * [Common Elements of three sorted arrays](sorted_array_three_common_elements.py)
+
+Find Common elements in three array given that all three arrays are sorted
 * [Dutch Flag Problem](dutch_flag_problem.py)
+ 
+ Given an array containing only 0s, 1s and 2s in a random order, arrange the array such that all 0s come 
+ before 1s which in turn come before all 2s
+
+Input - [1,2,0,1,2,1,0,1,2,1,0]
+
+Output - [0,0,0,1,1,1,1,1,2,2,2]
 * [Partition an array into three parts with equal sum](partition_three_parts_equal_sum.py)
-* [Binary search on an Infinite array](binary_search_infinite_array.py)
+
+Divide an array into three parts and sum all three parst must be same.
+* [Binary search on a finite array](binary_search_infinite_array.py)
+
+Performing binary search on a finite array
+
 * [Largest Element](largest_element.py)
-* [Right Place](right_place.py)
+
+Find out the largest element in an array
+
 * [Rotation](rotation.py)
+
+Rotate an array for given number such that the number goes to the end of array
+
+input=[1,2,3,4,5] rotate around 
+
+output= [4,5,1,2,3]
 * [Find missing number](find_missing_numbers.py)
+
+find missing number between smallest and largest number in array which are not present in array
+
+input=[1,1,1,4]
+output=[2,3]
+
 * [Three Largest Elements](three_largest_elements.py)
+
+Find three largest numbers from an array
 * [Triplet Sum](triplet_sum.py)
-* [Max Product](max_product.py)
+
+Find three elements of an array whose sum is eqaul to a given value
+
 * [Moves to Zero](moves_zeros_to_end.py)
+
+Given an array move all zeros in arrays to the end.
 * [Pivot Index](pivot_index.py)
+
+Find the index of element whose right element when added give the same value.
 * [Intersection of Two Sorted Arrays](intersection_sorted_array.py)
+
+ find out the common elements from two arrays
 * [Max Triplet Sum](max_triplet_sum.py)
-* [Number of 1's in Sorted Array](number_of_1_in_sorted_array.py)
+
+Find out maximium sum of any three elements for a given array
+
 * [Square of Sorted Array](square_of_sorted_array.py)
-* [Max Consecutive 1's](max_consecutive_ones.py)
-* [Max Product Three Elements](max_product_three_elements.py)
-* [Kadane Algorithm](kadane_algorithm.py)
+
+For a given array return an array that contains square of elements.
+
 * [All Numbers Divisible](all_numbers_divisible.py)
-* [Duplicates](duplicates.py)
+ 
+ Find a number in the array such that all the elements in the array are divisible by it
+ 
+
+
 * [Majority Element](majority_element.py)
+
+Find an element in an array which has most occurences
 * [Find Sum](find_sum.py)
+
+Find if sum of any elements in array is eqaul to a given number
 * [Quick Sort](quick_sort.py)
-* [Peak Element](peak_element.py)
+
+### Implement Quick Sort algorithm
+
+Quicksort Running Time:
+Quick sort average case is O(n log n)
+    each level takes O(n) but splitting the data is O(log n)
+    O(n) * O(log n) = O(n log n)
+Worse case is O(log n2)
+    if pivot is smallest value, each level is O(n) and splitting the data is O(n)
+    O(n) * O(n) = O(n2)
+
 * [Union Sorted Array](union_sorted_array.py)
-* [Min Product](min_product.py)
+
+Perform Union operations on two arrays
+
 * [Sort By Parity](sort_by_parity.py)
+
+Given an array A of non-negative integers, return an array consisting of all the even elements of A, followed by all the odd elements of A.
 * [Duplicate](duplicate.py)
-* [Product of Array Except Self](product_of_array_except_self.py)
+ 
+ Find duplicate in an array of integers given that the integers are in random order and 
+not necessarily each integer i is 0 <= i <= N where N = length of array
+* [Product of Array Except Self](product_of_array_except_self.py)
+
+find the product of all elements in an array 
+
+* [Right Place](right_place.py)
+
+Placing elements at right position in an array
+* [Max Product Three Elements](max_product_three_elements.py)
+
+Find out highest sum of three numbers in an array
+* [Max Consecutive 1's](max_consecutive_ones.py)
+
+Counts max number of one's in an array
+
+* [Kadane Algorithm](kadane_algorithm.py)
+
+Implementation of Kadane Algorithm
+* [Max Product](max_product.py)
+* [Number of 1's in Sorted Array](number_of_1_in_sorted_array.py)
+* [Duplicates](duplicates.py)
+* [Peak Element](peak_element.py)
+* [Min Product](min_product.py)
