LeetCode 157: Read N Characters Given Read4 Solution

Master LeetCode problem 157 (Read N Characters Given Read4), a easy challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

157. Read N Characters Given Read4

Easy

Array Simulation Interactive

Problem Explanation

Explanation:

In this problem, we are given a method read4 that reads 4 characters from a file and returns the number of characters read. Our task is to implement a method read that reads n characters from the file using the read4 method.

Algorithm:

Initialize a buffer buf to store the characters read.
Loop until either n characters have been read or the end of the file is reached:
- Read 4 characters using the read4 method.
- Copy the characters read from read4 to buf.
- Update the total characters read.
Return the minimum of n and the total characters read.

Time Complexity: O(n) - We read n characters from the file. Space Complexity: O(1) - We use a constant amount of extra space for variables.

: :

Solution Code

public class Solution extends Reader4 {
    public int read(char[] buf, int n) {
        char[] temp = new char[4];
        int total = 0;
        while (total < n) {
            int count = read4(temp);
            for (int i = 0; i < count && total < n; i++) {
                buf[total++] = temp[i];
            }
            if (count < 4) break;
        }
        return total;
    }
}

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