Leet Code 677. Map Sum Pairs

Example 1:

Input
["MapSum", "insert", "sum", "insert", "sum"]
[[], ["apple", 3], ["ap"], ["app", 2], ["ap"]]
Output
[null, null, 3, null, 5]

Explanation
MapSum mapSum = new MapSum();
mapSum.insert("apple", 3);  
mapSum.sum("ap");           // return 3 (apple = 3)
mapSum.insert("app", 2);    
mapSum.sum("ap");  

package pep.Day80;

import java.util.HashMap;

public class LeetCode_677_Map_Sum_Pairs {
    public static void main(String[] args) {

        insert("car", 1);
        insert("card", 4);
        insert("cards", 5);
        insert("carts", 6);
        insert("cars", 7);
        System.out.println(sum("ca"));
    }

    static class Node {
        Node[] children = new Node[26];
        int score = 0;
    }

    static Node root = new Node();
    static HashMap<String, Integer> map = new HashMap<>();

    public static void insert(String word, int val) {
        int diff = val - map.getOrDefault(word, 0);
        map.put(word, val);

        Node curr = root;
        for (int i = 0; i < word.length(); i++) {
            char ch = word.charAt(i);

            // alphabet exist nhi krta trie me to nae node bnaenge
            if (curr.children[ch - 'a'] == null) {
                curr.children[ch - 'a'] = new Node();

            }
            curr.children[ch - 'a'].score += diff;
            curr = curr.children[ch - 'a'];
        }

    }

    public static int sum(String prefix) {
        int sum = 0;
        Node curr = root;
        for (int i = 0; i < prefix.length(); i++) {
            char ch = prefix.charAt(i);
            if (curr.children[ch - 'a'] == null)
                return 0;
            curr = curr.children[ch - 'a'];
        }

        return curr.score;
    }
}