Pattern visualizer
Reverse the Array
Reversing doesn't need a second array or repeated shifting — swap the first and last elements, then the second and second-to-last, and so on, moving two pointers toward each other from opposite ends. Once they meet (or cross), every pair has been swapped exactly once. Animated on: arr = [1,2,3,4,5] — reverse the array in place..
Two pointers swap inward from both ends
time O(n)space O(1)step 1 / 5
1
[0]2
[1]3
[2]4
[3]5
[4]line 2
l=0, r=4: swap the outermost pair first, then move both pointers inward until they meet.
Pseudocode
1FUNCTION reverseArray(arr):2 l = 0, r = (the length of arr) - 13 WHILE l < r:4 swap arr[l] and arr[r]5 move l one step right; move r one step left6 RETURN arr
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