Read N Characters Given Read4 LeetCode Programming Solutions | LeetCode Problem Solutions in C++, Java, & Python [💯Correct]

LeetCode Problem | LeetCode Problems For Beginners | LeetCode Problems & Solutions | Improve Problem Solving Skills | LeetCode Problems Java | LeetCode Solutions in C++

Hello Programmers/Coders, Today we are going to share solutions to the Programming problems of LeetCode Solutions in C++, Java, & Python. At Each Problem with Successful submission with all Test Cases Passed, you will get a score or marks and LeetCode Coins. And after solving maximum problems, you will be getting stars. This will highlight your profile to the recruiters.

In this post, you will find the solution for the Read N Characters Given Read4 in C++, Java & Python-LeetCode problem. We are providing the correct and tested solutions to coding problems present on LeetCode. If you are not able to solve any problem, then you can take help from our Blog/website.

Use “Ctrl+F” To Find Any Questions Answer. & For Mobile User, You Just Need To Click On Three dots In Your Browser & You Will Get A “Find” Option There. Use These Option to Get Any Random Questions Answer.

About LeetCode

LeetCode is one of the most well-known online judge platforms to help you enhance your skills, expand your knowledge and prepare for technical interviews. 

LeetCode is for software engineers who are looking to practice technical questions and advance their skills. Mastering the questions in each level on LeetCode is a good way to prepare for technical interviews and keep your skills sharp. They also have a repository of solutions with the reasoning behind each step.

LeetCode has over 1,900 questions for you to practice, covering many different programming concepts. Every coding problem has a classification of either EasyMedium, or Hard.

LeetCode problems focus on algorithms and data structures. Here is some topic you can find problems on LeetCode:

  • Mathematics/Basic Logical Based Questions
  • Arrays
  • Strings
  • Hash Table
  • Dynamic Programming
  • Stack & Queue
  • Trees & Graphs
  • Greedy Algorithms
  • Breadth-First Search
  • Depth-First Search
  • Sorting & Searching
  • BST (Binary Search Tree)
  • Database
  • Linked List
  • Recursion, etc.

Leetcode has a huge number of test cases and questions from interviews too like Google, Amazon, Microsoft, Facebook, Adobe, Oracle, LinkedIn, Goldman Sachs, etc. LeetCode helps you in getting a job in Top MNCs. To crack FAANG Companies, LeetCode problems can help you in building your logic.

Link for the ProblemRead N Characters Given Read4– LeetCode Problem

Read N Characters Given Read4– LeetCode Problem

Problem:

Given a file and assume that you can only read the file using a given method read4, implement a method to read n characters.

Method read4:

The API read4 reads four consecutive characters from file, then writes those characters into the buffer array buf4.

The return value is the number of actual characters read.

Note that read4() has its own file pointer, much like FILE *fp in C.

Definition of read4:

    Parameter:  char[] buf4
    Returns:    int

buf4[] is a destination, not a source. The results from read4 will be copied to buf4[].

Below is a high-level example of how read4 works:

157 example
File file("abcde"); // File is "abcde", initially file pointer (fp) points to 'a'
char[] buf4 = new char[4]; // Create buffer with enough space to store characters
read4(buf4); // read4 returns 4. Now buf4 = "abcd", fp points to 'e'
read4(buf4); // read4 returns 1. Now buf4 = "e", fp points to end of file
read4(buf4); // read4 returns 0. Now buf4 = "", fp points to end of file

Method read:

By using the read4 method, implement the method read that reads n characters from file and store it in the buffer array buf. Consider that you cannot manipulate file directly.

The return value is the number of actual characters read.

Definition of read:

    Parameters:	char[] buf, int n
    Returns:	int

buf[] is a destination, not a source. You will need to write the results to buf[].

Note:

  • Consider that you cannot manipulate the file directly. The file is only accessible for read4 but not for read.
  • The read function will only be called once for each test case.
  • You may assume the destination buffer array, buf, is guaranteed to have enough space for storing n characters.

Example 1:

Input: file = "abc", n = 4
Output: 3
Explanation: After calling your read method, buf should contain "abc". We read a total of 3 characters from the file, so return 3.
Note that "abc" is the file's content, not buf. buf is the destination buffer that you will have to write the results to.

Example 2:

Input: file = "abcde", n = 5
Output: 5
Explanation: After calling your read method, buf should contain "abcde". We read a total of 5 characters from the file, so return 5.

Example 3:

Input: file = "abcdABCD1234", n = 12
Output: 12
Explanation: After calling your read method, buf should contain "abcdABCD1234". We read a total of 12 characters from the file, so return 12.

Example 4:

Input: file = "leetcode", n = 5
Output: 5
Explanation: After calling your read method, buf should contain "leetc". We read a total of 5 characters from the file, so return 5.

Constraints:

  • 1 <= file.length <= 500
  • file consist of English letters and digits.
  • 1 <= n <= 1000
Read N Characters Given Read4– LeetCode Solutions
Read N Characters Given Read4  Solution in C++:
/**
 * The read4 API is defined in the parent class Reader4.
 *     int read4(char *buf4);
 */

class Solution {
 public:
  /**
   * @param buf Destination buffer
   * @param n   Number of characters to read
   * @return    The number of actual characters read
   */
  int read(char* buf, int n) {
    char* buf4 = new char[4];
    int i4 = 0;  // buf4's index
    int n4 = 0;  // buf4's size
    int i = 0;   // buf's index

    while (i < n) {
      if (i4 == n4) {      // all characters in buf4 are consumed
        i4 = 0;            // reset buf4's index
        n4 = read4(buf4);  // read 4 (or less) chars from file to buf4
        if (n4 == 0)       // reach the EOF
          return i;
      }
      buf[i++] = buf4[i4++];
    }

    return i;
  }
};
Read N Characters Given Read4 Solution in Java:
/**
 * The read4 API is defined in the parent class Reader4.
 *     int read4(char[] buf4);
 */

public class Solution extends Reader4 {
  /**
   * @param buf Destination buffer
   * @param n   Number of characters to read
   * @return The number of actual characters read
   */
  public int read(char[] buf, int n) {
    char[] buf4 = new char[4];
    int i4 = 0; // buf4's index
    int n4 = 0; // buf4's size
    int i = 0;  // buf's index

    while (i < n) {
      if (i4 == n4) {     // all characters in buf4 are consumed
        i4 = 0;           // reset buf4's index
        n4 = read4(buf4); // read 4 (or less) chars from file to buf4
        if (n4 == 0)      // reach the EOF
          return i;
      }
      buf[i++] = buf4[i4++];
    }

    return i;
  }
}
Read N Characters Given Read4 Solution in Python:
"""
The read4 API is already defined for you.
    def read4(buf4: List[chr]) -> int:

# Below is an example of how the read4 API can be called.
file = File("abcdefghijk") # File is "abcdefghijk", initially file pointer (fp) points to 'a'
buf4 = [' '] * 4 # Create buffer with enough space to store characters
read4(buf4) # read4 returns 4. Now buf = ['a','b','c','d'], fp points to 'e'
read4(buf4) # read4 returns 4. Now buf = ['e','f','g','h'], fp points to 'i'
read4(buf4) # read4 returns 3. Now buf = ['i','j','k',...], fp points to end of file
"""


class Solution:
  def read(self, buf: List[str], n: int) -> int:
    buf4 = [' '] * 4
    i4 = 0  # buf4's index
    n4 = 0  # buf4's size
    i = 0  # buf's index

    while i < n:
      if i4 == n4:  # all characters in buf4 are consumed
        i4 = 0  # reset buf4's index
        n4 = read4(buf4)  # read 4 (or less) chars from file to buf4
        if n4 == 0:  # reach the EOF
          return i
      buf[i] = buf4[i4]
      i += 1
      i4 += 1

    return i

Leave a Comment

Ads Blocker Image Powered by Code Help Pro
Ads Blocker Detected!!!

We have detected that you are using extensions to block ads. Please support us by disabling these ads blocker.

Refresh
Powered By
CHP Adblock Detector Plugin | Codehelppro