1598-CrawlerLogFolder.go

package main

// 1598. Crawler Log Folder
// The Leetcode file system keeps a log each time some user performs a change folder operation.
// The operations are described below:
//     "../" : Move to the parent folder of the current folder. (If you are already in the main folder, remain in the same folder).
//     "./" : Remain in the same folder.
//     "x/" : Move to the child folder named x (This folder is guaranteed to always exist).

// You are given a list of strings logs where logs[i] is the operation performed by the user at the ith step.
// The file system starts in the main folder, then the operations in logs are performed.
// Return the minimum number of operations needed to go back to the main folder after the change folder operations.

// Example 1:
// <img src="https://assets.leetcode.com/uploads/2020/09/09/sample_11_1957.png" />
// Input: logs = ["d1/","d2/","../","d21/","./"]
// Output: 2
// Explanation: Use this change folder operation "../" 2 times and go back to the main folder.

// Example 2:
// <img src="https://assets.leetcode.com/uploads/2020/09/09/sample_22_1957.png" />
// Input: logs = ["d1/","d2/","./","d3/","../","d31/"]
// Output: 3

// Example 3:
// Input: logs = ["d1/","../","../","../"]
// Output: 0

// Constraints:
//     1 <= logs.length <= 10^3
//     2 <= logs[i].length <= 10
//     logs[i] contains lowercase English letters, digits, '.', and '/'.
//     logs[i] follows the format described in the statement.
//     Folder names consist of lowercase English letters and digits.

import "fmt"

func minOperations(logs []string) int {
    res := 0
    for _, v := range logs {
        if v == "./" {
            continue
        }
        if v == "../" {
            if res > 0 { // 不在顶层才做处理
                res--
            }
        } else {
            res++
        }
    }
    return res
}

func main() {
    // Example 1:
    // <img src="https://assets.leetcode.com/uploads/2020/09/09/sample_11_1957.png" />
    // Input: logs = ["d1/","d2/","../","d21/","./"]
    // Output: 2
    // Explanation: Use this change folder operation "../" 2 times and go back to the main folder.
    fmt.Println(minOperations([]string{"d1/","d2/","../","d21/","./"})) // 2
    // Example 2:
    // <img src="https://assets.leetcode.com/uploads/2020/09/09/sample_22_1957.png" />
    // Input: logs = ["d1/","d2/","./","d3/","../","d31/"]
    // Output: 3
    fmt.Println(minOperations([]string{"d1/","d2/","./","d3/","../","d31/"})) // 3
    // Example 3:
    // Input: logs = ["d1/","../","../","../"]
    // Output: 0
    fmt.Println(minOperations([]string{"d1/","../","../","../"})) // 0
}