See the two pointers technique step by step: watch left and right close in on a sorted array in an animated Python visualization (Two Sum II, LeetCode 167).
Examples▶Open the visualizer
Algorithm Visualization Examples in Python
The algorithm patterns that come up again and again in LeetCode problems and coding interviews. Each example explains the idea, shows a short Python solution and opens it in the visualizer, where you can watch it run line by line: pointers moving over arrays, trees and grids being explored, the call stack growing and shrinking.
Watch a sliding window grow and shrink over a string, step by step, in an animated Python visualization (Longest Substring Without Repeating Characters).
Visualize binary search step by step: see lo, mid and hi move over a sorted array and the search space halve on every comparison (LeetCode 704).
See how reversing a linked list works: watch prev, curr and next move and each arrow flip, step by step, in an animated Python visualization (LeetCode 206).
Visualize breadth-first search on a binary tree: watch the queue and the tree level by level in an animated Python step-by-step trace (LeetCode 102).
Watch breadth-first search flood-fill a 2D grid step by step. An animated Python visualization of Number of Islands (LeetCode 200) with the matrix and queue.
Visualize recursion and backtracking with the call stack: watch every recursive call push and pop while generating all subsets, step by step (LeetCode 78).
See a bottom-up dynamic programming table fill in, step by step. Animated Python visualization of Coin Change (LeetCode 322) with the dp array.