# 811. Subdomain Visit Count

Medium
A website domain `"discuss.leetcode.com"` consists of various subdomains. At the top level, we have `"com"`, at the next level, we have `"leetcode.com"` and at the lowest level, `"discuss.leetcode.com"`. When we visit a domain like `"discuss.leetcode.com"`, we will also visit the parent domains `"leetcode.com"` and `"com"` implicitly.
A count-paired domain is a domain that has one of the two formats `"rep d1.d2.d3"` or `"rep d1.d2"` where `rep` is the number of visits to the domain and `d1.d2.d3` is the domain itself.
• For example, `"9001 discuss.leetcode.com"` is a count-paired domain that indicates that `discuss.leetcode.com` was visited `9001` times.
Given an array of count-paired domains `cpdomains`, return an array of the count-paired domains of each subdomain in the input. You may return the answer in any order.
Example 1:
Input: cpdomains = ["9001 discuss.leetcode.com"]
Output: ["9001 leetcode.com","9001 discuss.leetcode.com","9001 com"]
Explanation: We only have one website domain: "discuss.leetcode.com".
As discussed above, the subdomain "leetcode.com" and "com" will also be visited. So they will all be visited 9001 times.
Example 2:
Input: cpdomains = ["900 google.mail.com", "50 yahoo.com", "1 intel.mail.com", "5 wiki.org"]
Output: ["901 mail.com","50 yahoo.com","900 google.mail.com","5 wiki.org","5 org","1 intel.mail.com","951 com"]
Explanation: We will visit "google.mail.com" 900 times, "yahoo.com" 50 times, "intel.mail.com" once and "wiki.org" 5 times.
For the subdomains, we will visit "mail.com" 900 + 1 = 901 times, "com" 900 + 50 + 1 = 951 times, and "org" 5 times.
Constraints:
• `1 <= cpdomain.length <= 100`
• `1 <= cpdomain[i].length <= 100`
• `cpdomain[i]` follows either the `"repi d1i.d2i.d3i"` format or the `"repi d1i.d2i"` format.
• `repi` is an integer in the range `[1, 10^4]`.
• `d1i`, `d2i`, and `d3i` consist of lowercase English letters.

### 解題

func subdomainVisits(cpdomains []string) []string {
m := make(map[string]int) // 記錄每個網域被拜訪的次數
for _, s := range cpdomains {
arr := strings.Fields(s) // 將次數與domain name 分開
times, domain := arr[0], arr[1]
time, err := strconv.Atoi(times) // 將次數轉為次數，才能做加法
if err != nil { fmt.Println(err) }
m[domain] += time // 將一開始的domain次數記錄起來
for i:=0; i<len(domain); i++ {
if domain[i] == '.' { // 依序遞迴subdomain
m[domain[i+1:]] += time // 記錄subdomain被拜訪的次數
}
}
}
ans := make([]string, 0)
for key := range m {
ans = append(ans, strconv.Itoa(m[key]) + " " + key)
}
return ans
}