158. Read N Characters Given Read4 II - Call multiple times

Posted 2020-12-30 tobeabetterpig

158. Read N Characters Given Read4 II - Call multiple times




Given buf = "abc"
read("abc", 1) // returns "a"
read("abc", 2); // returns "bc"
read("abc", 1); // returns ""
Example 2: 

Given buf = "abc"
read("abc", 4) // returns "abc"
read("abc", 1); // returns ""

   

    private int buffPtr = 0;
    private int buffCnt = 0;
    private char[] buff = new char[4];
    public int read(char[] buf, int n) {
        int ptr = 0;
        while (ptr < n) {
            if (buffPtr == 0) {
                buffCnt = read4(buff);
            }
          
            if (buffCnt == 0) break;
          
            while (ptr < n && buffPtr < buffCnt) {
                buf[ptr++] = buff[buffPtr++];
            }
          
            if (buffPtr >= buffCnt){
              buffPtr = 0;
            }
        }
        return ptr;
    }
I used buffer pointer (buffPtr) and buffer Counter (buffCnt)
  to store the data received
in previous calls. In the while loop,
if buffPtr reaches current buffCnt, it will be set
as zero to be ready to read new data.