Won't you just stick to 62 days? Sum of words

class MapSum {
    Map<String, Integer> map;

    public MapSum() {
        map = new HashMap<>();
    }
    
    public void insert(String key, int val) {
        map.put(key,val);
    }
    
    public int sum(String prefix) {
        int res = 0;
        for (String s : map.keySet()) {
            if (s.startsWith(prefix)) {
                res += map.get(s);
            }
        }
        return res;
    }
}

 author ：LeetCode-Solution
 link ：https://leetcode.cn/problems/z1R5dt/solution/dan-ci-zhi-he-by-leetcode-solution-8vyo/
 source ： Power button （LeetCode）
 The copyright belongs to the author . Commercial reprint please contact the author for authorization , Non-commercial reprint please indicate the source .

 

class MapSum {
    Map<String, Integer> map;
    Map<String, Integer> prefixmap;

    public MapSum() {
        map = new HashMap<>();
        prefixmap = new HashMap<>();
    }
    
    public void insert(String key, int val) {
        int delta = val - map.getOrDefault(key, 0);
        map.put(key, val);
        for (int i = 1; i <= key.length(); ++i) {
            String currprefix = key.substring(0, i);
            prefixmap.put(currprefix, prefixmap.getOrDefault(currprefix, 0) + delta);
        }
    }
    
    public int sum(String prefix) {
        return prefixmap.getOrDefault(prefix, 0);
    }
}

 author ：LeetCode-Solution
 link ：https://leetcode.cn/problems/z1R5dt/solution/dan-ci-zhi-he-by-leetcode-solution-8vyo/
 source ： Power button （LeetCode）
 The copyright belongs to the author . Commercial reprint please contact the author for authorization , Non-commercial reprint please indicate the source .