157. Read N Characters Given Read4
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
bufto store the characters read. - Loop until either
ncharacters have been read or the end of the file is reached:- Read 4 characters using the
read4method. - Copy the characters read from
read4tobuf. - Update the total characters read.
- Read 4 characters using the
- Return the minimum of
nand 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.
: :
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;
}
}Code Editor (Testing phase)
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