157_Read_N_Characte_Given_Read4

Author: Partho Biswas

README.md

@@ -253,6 +253,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |42| [415. Add Strings](https://tinyurl.com/y7cbq62x) | [Python](https://tinyurl.com/wu6rdaw/415_Add_Strings.py), [Swift](https://tinyurl.com/wuja3c4/415_Add_Strings.swift) | [Art 1](https://tinyurl.com/y6v9uj9o) | Easy | --- |
 |43| **[65. Valid Number](https://tinyurl.com/yb6zsj3b)** | [Python](https://tinyurl.com/wu6rdaw/65_Valid_Number.py), [Swift](https://tinyurl.com/wuja3c4/65_Valid_Number.swift) | [Art 1](https://tinyurl.com/ycotov9v) | HARD | A fucking difficult but important problem. Chack DFA approach |
 |44| **[791. Custom Sort String](https://tinyurl.com/yag8mcfd)** | [Python](https://tinyurl.com/wu6rdaw/791_Custom_Sort_String.py), [Swift](https://tinyurl.com/wuja3c4/791_Custom_Sort_String.swift) | --- | Medium | Loved this problem |
+|45| **[157. Read N Characters Given Read4](https://tinyurl.com/y5g49nqt)** | [Python](https://tinyurl.com/wu6rdaw/157_Read_N_Characte_Given_Read4.py), [Swift](https://tinyurl.com/wuja3c4/157_Read_N_Characte_Given_Read4.swift) | --- | Easy (Not So!) | Loved this problem |
 
 
 </p>

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/157_Read_N_Characte_Given_Read4.swift

@@ -0,0 +1,34 @@
+/**
+ * The read4 API is defined in the parent class Reader4.
+ *     func read4(_ buf4: inout [Character]) -> Int;
+ */
+
+// Appriach 1
+class Solution : Reader4 {
+    /**
+     * @param buf Destination buffer
+     * @param n   Number of characters to read
+     * @return    The number of actual characters read
+     */
+    func read(_ buf: inout [Character], _ n: Int) -> Int {
+        guard n > 0 else {
+            return 0
+        }
+        var (copiedChars, readChars) = (0, 4)
+        var buf4: [Character] = ["c", "a", "t", "!"]
+        
+        while copiedChars < n && readChars == 4 {
+            readChars = super.read4(&buf4)
+            
+            for i in 0..<readChars {
+                if copiedChars == n {
+                    return copiedChars
+                }
+                buf[copiedChars] = buf4[i]
+                copiedChars += 1
+            }
+        }
+        return copiedChars
+    }
+}
+