[677. Map Sum Pairs] #leetcode

677_0923.java

class MapSum {
    class TrieNode {
        int val;
        Map<Character, TrieNode> next;
        boolean isWord;

        public TrieNode() {
            val = 0;
            next = new HashMap<Character, TrieNode>();
            isWord = false;
        }
    }


    /** Initialize your data structure here. */
    TrieNode root;
    
    public MapSum() {
        root = new TrieNode();
    }
    
    public void insert(String key, int val) {
        TrieNode node = root;
        
        for (char c : key.toCharArray()) {
            if (!node.next.containsKey(c)) {
                TrieNode child = new TrieNode();
                node.next.put(c, child);
            }
            node = node.next.get(c);
        }
        
        node.val = val;
    }
    
    public int sum(String prefix) {
        TrieNode node = root;
        
        for (char c : prefix.toCharArray()) {
            if (!node.next.containsKey(c)) {
                return 0;
            }
            node = node.next.get(c);
        }
        
        return dfs(node);
        
    }
    
    private int dfs(TrieNode root) {
        int sum = 0;
        for (char c : root.next.keySet()) {
            sum += dfs(root.next.get(c));
        }
        return sum + root.val;
    }
}


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


class MapSum {
    
    Map<String, Integer> map;
    Map<String, Integer> original;
    
    /** Initialize your data structure here. */
    public MapSum() {
        map = new HashMap<>();
        original = new HashMap<>();
    }
    
    public void insert(String key, int val) {
        int diff = val - original.getOrDefault(key, 0);
        String s = "";
        map.put(s, map.getOrDefault(s, 0) + diff);
        
        for (char c : key.toCharArray()) {
            s += c;
            map.put(s, map.getOrDefault(s, 0) + diff);
        }
        original.put(key, original.getOrDefault(key, 0) + diff);
    }
    
    public int sum(String prefix) {
        return map.getOrDefault(prefix, 0);
    }
}