Better with Turbowarp ( high quality pen,16:9 screen, 60fps ) : https://turbowarp.org/672804796?fps=60&size=640x360&offscreen&hqpen This is a Binary Indexed Tree (or Fenwick Tree) playground with 2 functions: add(x) & ask(x). On each node is a number shows the value of that node. When pressing add button it will show the path of the points added value. When pressing ask button it will show a light blue path, it means the result is the sum of all the nodes in that path, it also shows some yellow, red or blue paths shows why the function ask(x) can get the result by counting the sum of just log(x) points. #Binary-Indexed-Tree #Fenwick-Tree #data-structure #playground #tree-data-structure #data #tree #BIT #visualization