solves #157: Read N Characters Given Read 4 in java

Author: anishLearnsToCode

README.md

@@ -151,7 +151,7 @@
 | 153  | [Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array)                                                             |                                                                               [![Java](assets/java.png)](src/FindMinimumInRotatedSortedArray.java)                                                                               |                                                                                                                                   |
 | 155  | [Min Stack](https://leetcode.com/problems/min-stack)                                                                                                                   |                                                                [![Java](assets/java.png)](src/MinStack.java) [![Python](assets/python.png)](python/min_stack.py)                                                                 |                                                                                                                                   |
 | 156  | 🔒 [Binary Tree Upside Down](https://leetcode.com/problems/binary-tree-upside-down)                                                                                    |                                                                                                                                                                                                                                  |                                                                                                                                   |
-| 157  | [Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4)                                                                           |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 157  | 🔒 [Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4)                                                                        |                                                                                  [![Java](assets/java.png)](src/ReadNCharactersGivenRead4java)                                                                                   |                                                                                                                                   |
 | 159  | 🔒 [Longest Substring With At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters)                      |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 160  | [Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists)                                                                     |                                           [![Java](assets/java.png)](src/IntersectionOf2LinkedLists.java) [![Python](assets/python.png)](python/intersecction_of_two_linked_lists.py)                                            |                                                                                                                                   |
 | 161  | 🔒 [One Edit Distance](https://leetcode.com/problems/one-edit-distance)                                                                                                |                                                                                                                                                                                                                                  |                                                                                                                                   |

src/ReadNCharactersGivenRead4.java

@@ -0,0 +1,29 @@
+// https://leetcode.com/problems/read-n-characters-given-read4
+// T: O(N)
+// S: O(1)
+
+public class ReadNCharactersGivenRead4 {
+    static class Reader4 {
+        public int read4(char[] buffer) {
+            return 0;
+        }
+    }
+
+    static class Solution extends Reader4 {
+        public int read(char[] buf, int n) {
+            int copiedChars = 0, readChars = 4;
+            char[] buf4 = new char[4];
+
+            while (copiedChars < n && readChars == 4) {
+                readChars = read4(buf4);
+
+                for (int i = 0; i < readChars; ++i) {
+                    if (copiedChars == n) return copiedChars;
+                    buf[copiedChars] = buf4[i];
+                    ++copiedChars;
+                }
+            }
+            return copiedChars;
+        }
+    }
+}