Brackets

Determine whether a given string of parentheses (multiple types) is properly nested.

A string S consisting of N characters is considered to be properly nested if any of the following conditions is true:

S is empty; S has the form "(U)" or "[U]" or "{U}" where U is a properly nested string; S has the form "VW" where V and W are properly nested strings. For example, the string "{[()()]}" is properly nested but "([)()]" is not.

Write a function:

func Solution(S string) int

that, given a string S consisting of N characters, returns 1 if S is properly nested and 0 otherwise.

For example, given S = "{[()()]}", the function should return 1 and given S = "([)()]", the function should return 0, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..200,000]; string S consists only of the following characters: "(", "{", "[", "]", "}" and/or ")". Copyright 2009–2021 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

題目大意

括號配對, 可配對回傳1 反之回傳0.

解題思路

將左括號都放入stack. 遇到右括號時將stack pop出來並檢查pop出來的左括號是否跟右括號配對.

來源

https://app.codility.com/programmers/lessons/7-stacks_and_queues/brackets/

解答

https://github.com/kimi0230/LeetcodeGolang/blob/master/Codility/Lesson/0007.Stacks-and-Queues/Brackets/Brackets.go

package Brackets

import (
    "LeetcodeGolang/Utility/structures"
)

func Solution(S string) int {
    if len(S) == 0 {
        return 1
    }
    if len(S)%2 != 0 {
        return 0
    }

    BracketMap := map[string]string{
        ")": "(",
        "]": "[",
        "}": "{",
    }

    stack := structures.NewArrayStack()
    for _, v := range S {
        val := string(v)
        if val == "(" || val == "[" || val == "{" {
            stack.Push(val)
        } else if val == ")" || val == "]" || val == "}" {
            if stack.IsEmpty() {
                return 0
            }

            topVal := stack.Top()
            if topVal == BracketMap[val] {
                stack.Pop()
            } else {
                // 找不到可配對的括號
                return 0
            }
        }
    }
    if stack.IsEmpty() {
        return 1
    } else {
        return 0
    }
}