LeetCode - #158 用 Read4 读取 N 个字符 II

class Solution {
    private var buffer: [Character] = [] // 缓存从 read4 读取的多余字符
    private var bufferPointer = 0       // 缓存指针位置
    private var bufferSize = 0          // 当前缓存中的字符数量

    func read4(_ buf: inout [Character]) -> Int {
        // 模拟 read4 方法
        return 0 // 此方法由系统实现，用户无需实现此部分
    }

    func read(_ buf: inout [Character], _ n: Int) -> Int {
        var totalRead = 0
        var tempBuf = [Character](repeating: "\0", count: 4) // 临时缓冲区

        while totalRead < n {
            // 如果缓存为空，则调用 read4 填充缓存
            if bufferPointer == bufferSize {
                bufferSize = read4(&tempBuf)
                bufferPointer = 0

                // 如果 read4 读取到文件末尾，则停止
                if bufferSize == 0 {
                    break
                }

                // 更新缓存
                buffer = Array(tempBuf[0..<bufferSize])
            }

            // 从缓存中读取字符到 buf
            while bufferPointer < bufferSize && totalRead < n {
                buf.append(buffer[bufferPointer])
                bufferPointer += 1
                totalRead += 1
            }
        }

        return totalRead
    }
}

// 模拟一个文件内容
let fileContent = "abcdefghijk"
var solution = Solution()

// 初始化输出缓存
var outputBuffer: [Character] = []

// 调用 read 方法
var result1 = solution.read(&outputBuffer, 4)
print("读取到的字符数：\(result1), 缓存内容：\(String(outputBuffer))")

outputBuffer = []
var result2 = solution.read(&outputBuffer, 5)
print("读取到的字符数：\(result2), 缓存内容：\(String(outputBuffer))")

outputBuffer = []
var result3 = solution.read(&outputBuffer, 4)
print("读取到的字符数：\(result3), 缓存内容：\(String(outputBuffer))")

读取到的字符数：4, 缓存内容：abcd
读取到的字符数：5, 缓存内容：efghi
读取到的字符数：2, 缓存内容：jk