LEETCODE 113 (JAVASCRIPT) | PATH SUM II

Hey everyone. Check out this in-depth solution for leetcode 113.

[@sajalgupta7345]

Hey Andy, Why did we do slate.slice() on line 23. Wouldn't slate and slate.slice() be the same thing as both will returns the array only.

[@sourenasahraian2055]

They are but only at that point, Arrays are passed around by reference , so any change you do the same slate instance as it gets passed around up and down the tree(future push /pop ) are also reflected into the result . You want your hard earned path solutions to be snapshots in time and remain intact . If you don't copy the array , the same address in memory gets passed around and your data will get corrupt.

[@TekkenRoom]

that's also an alternative line " paths.push([...slate])"

[@user-pm2kx1vi1e]

/** * Definition for a binary tree node. * function TreeNode(val, left, right) { * this.val = (val===undefined ? 0 : val) * this.left = (left===undefined ? null : left) * this.right = (right===undefined ? null : right) * } */ /** * @param {TreeNode} root * @param {number} targetSum * @return {number[][]} */ var pathSum = function(root, targetSum) { if(!root) return []; const paths=[]; const dfs = (node, sum, slate) => { if(node.left === null && node.right === null){ if(sum === node.val){ slate.push(node.val); paths.push(slate.slice()); slate.pop(); } } if(node.left){ slate.push(node.val); dfs(node.left, sum - node.val, slate); slate.pop(); } if(node.right){ slate.push(node.val); dfs(node.left, sum - node.val, slate); slate.pop(); } } dfs(root, targetSum, []); return paths; };;