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// @Title: 键值映射 (Map Sum Pairs)
// @Author: 15816537946@163.com
// @Date: 2021-11-14 02:16:53
// @Runtime: 0 ms
// @Memory: 2.9 MB
type MapSum struct {
    root map[byte]*node
}

type node struct {
    cnt int 
    isEnd bool 
    next map[byte]*node
}

func Constructor() MapSum {
    var a MapSum 
    a.root = make(map[byte]*node)

    return a
}

func (this *MapSum) Insert(key string, val int)  {
    cur := this.root
    end := len(key)-1

    for i := range key {
        if _,ok := cur[key[i]];!ok {
            newNode := node{
                next : make(map[byte]*node),
            }
            cur[key[i]] = &newNode
        }
        if i == end {
            break
        }
        cur = cur[key[i]].next
    }

    cur[key[end]].cnt = val
    cur[key[end]].isEnd = true
}


func (this *MapSum) Sum(prefix string) int {
    cur := this.root
    end := len(prefix)-1
    var ret int 

    for i := range prefix {
        if _, ok := cur[prefix[i]];!ok {
            return ret
        } else {
            if i == end && cur[prefix[end]].isEnd{
                ret += cur[prefix[end]].cnt
            }
            cur = cur[prefix[i]].next
        }
    }

    var dfs func(map[byte]*node)
    dfs = func(n map[byte]*node)  {
    if n == nil {
        return 
    }

    for _,v := range  n {
        if v.isEnd {
            ret +=v.cnt
        }
        dfs(v.next)
    }
    }

    dfs(cur)

    return ret

}




/**
 * Your MapSum object will be instantiated and called as such:
 * obj := Constructor();
 * obj.Insert(key,val);
 * param_2 := obj.Sum(prefix);
 */