Palindrome Pairs - Efficient Solution with Trie Data Structure

The error you're encountering is related to accessing the childs property of this.order[p1] which is undefined. This occurs because the array this.order is initialized with new Array<Tree>(1500000), creating an array of a given length but with uninitialized elements. To resolve this, initialize each element of the this.order and this.rever arrays with empty Tree objects before accessing their properties. You can achieve this by looping through the arrays and assigning an empty Tree object to each element. For instance, within the constructor: \n\ntypescript\nconstructor() {\n this.rever = new Array<Tree>(1500000);\n this.order = new Array<Tree>(1500000);\n this.reverCnt = 0;\n this.orderCnt = 0;\n\n for (let i = 0; i < 1500000; i++) {\n this.rever[i] = { index: 0, childs: [] };\n this.order[i] = { index: 0, childs: [] };\n }\n}\n\n\nThis ensures that each element in the this.order and this.rever arrays is initialized with a Tree object containing an empty childs array. This prevents the error by guaranteeing that this.order[p1] and this.rever[p] always have a valid childs property available.