The API: int read4(char *buf) reads 4 characters at a time from a file.

The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file.

By using the read4 API, implement the function int read(char *buf, int n) that reads n characters from the file.



The read function will only be called once for each test case.

Thought Process

  1. Extra Buffer Array and Pointer
    1. Read and store the characters in a temporary buffer
    2. Then append the character until we reach the end of file or the nth character
    3. Time complexity O(n)
    4. Space complexity O(1)


/* The read4 API is defined in the parent class Reader4.
      int read4(char[] buf); */

public class Solution extends Reader4 {
     * @param buf Destination buffer
     * @param n   Maximum number of characters to read
     * @return    The number of characters read
    public int read(char[] buf, int n) {
        char[] tmp = new char[4];
        int total = 0;
        while (total < n) {
            int count = read4(tmp);
            int len = Math.min(count, n - total);
            for (int i = 0; i < len; i++) {
                buf[total++] = tmp[i];
            if (count < 4) break;
        return total;

results matching ""

    No results matching ""