循环buffer，基于数组实现pop和push

1、 字符串中 "(" , ")" 是否匹配？

func find(list: String) -> Bool {
    var num : Int = 0
    for str in list.characters {
        if str == "(" {
            num += 1
        } else if str == ")" {
            if num > 0 {
                num -= 1
            } else {
                return false
            }
        }
    }
    if num == 0 {
        return true
    }
    return false
}

let value = find(list: "(3+4)(5+6)(6(7+8)-8)((()))")

2、循环buffer，基于数组，实现pop和push。

循环队列判断空和满的条件.png

class CircleBuff {
    private var size: Int = 0  // 真正size = size - 1
    private var start: Int = 0 // 将要pop的Index
    private var end: Int = 0   // 将要push的Index
    private var array: [Int?] = []
    
    init(size: Int) {
        self.size = size
        for _ in 0 ..< size {
            array.append(nil)
        }
    }
    
    func pop()-> Int? {
        print("")
        print("pop" )
        if isEmpty() {
            print("quene is empty!")
            return nil
        }
        let value = array[start]
        array[start] = nil
        start += 1
        if start >= size {
            start = 0
        }
        print(array)
        print("start:" + "\(start)" )
        print("end:" + "\(end)" )
        return value
    }
    
    func push(_ param: Int) {
        print("")
        print("push" )
        if isFull() {
            
            print("quene is full!")
            print("插入失败:" + "\(param)")
            return
        }
        array[end] = param
        end += 1
        if end >= size {
           end = 0
        }
        print(array)
        print("start:" + "\(start)" )
        print("end:" + "\(end)" )
    }
    
    func isEmpty() -> Bool {
        if start == end {
            return true
        }
        return false
    }
    
    func isFull() -> Bool {
        if  (end + 1) % size == start {
            return true
        }
        return false
    }
}

let buff = CircleBuff.init(size: 5)
buff.push(1)
buff.push(2)
buff.push(3)
buff.push(4)
buff.push(5)
buff.push(6)
buff.push(7)
buff.push(8)
buff.push(9)
buff.push(10)


buff.pop()
buff.pop()

buff.push(11)
buff.push(12)
buff.push(13)