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package g0601_0700.s0677_map_sum_pairs;

// #Medium #String #Hash_Table #Design #Trie #2022_03_22_Time_17_ms_(70.10%)_Space_43.5_MB_(21.07%)

/**
 * 677 - Map Sum Pairs\.
 *
 * Medium
 *
 * Design a map that allows you to do the following:
 *
 * *   Maps a string key to a given value.
 * *   Returns the sum of the values that have a key with a prefix equal to a given string.
 *
 * Implement the `MapSum` class:
 *
 * *   `MapSum()` Initializes the `MapSum` object.
 * *   `void insert(String key, int val)` Inserts the `key-val` pair into the map. If the `key` already existed, the original `key-value` pair will be overridden to the new one.
 * *   `int sum(string prefix)` Returns the sum of all the pairs' value whose `key` starts with the `prefix`.
 *
 * **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"); // return 5 (apple + app = 3 + 2 = 5)
 *
 * **Constraints:**
 *
 * *   `1 <= key.length, prefix.length <= 50`
 * *   `key` and `prefix` consist of only lowercase English letters.
 * *   `1 <= val <= 1000`
 * *   At most `50` calls will be made to `insert` and `sum`.
**/
public class MapSum {
    static class Node {
        int val;
        Node[] child;

        Node() {
            child = new Node[26];
            val = 0;
        }
    }

    private final Node root;

    public MapSum() {
        root = new Node();
    }

    public void insert(String key, int val) {
        Node curr = root;
        for (char c : key.toCharArray()) {
            if (curr.child[c - 'a'] == null) {
                curr.child[c - 'a'] = new Node();
            }
            curr = curr.child[c - 'a'];
        }
        curr.val = val;
    }

    private int sumHelper(Node root) {
        int o = 0;
        for (int i = 0; i < 26; i++) {
            if (root.child[i] != null) {
                o += root.child[i].val + sumHelper(root.child[i]);
            }
        }
        return o;
    }

    public int sum(String prefix) {
        Node curr = root;
        for (char c : prefix.toCharArray()) {
            if (curr.child[c - 'a'] == null) {
                return 0;
            }
            curr = curr.child[c - 'a'];
        }
        int sum = curr.val;
        return sum + sumHelper(curr);
    }
}

/*
 * Your MapSum object will be instantiated and called as such:
 * MapSum obj = new MapSum();
 * obj.insert(key,val);
 * int param_2 = obj.sum(prefix);
 */