Reverse String - Day 4

Author: suriyakrishna

src/main/java/com/kishan/java/leetcode/juneChallenges/ReverseString.java

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+package com.kishan.java.leetcode.juneChallenges;
+
+/*
+ * Two pointer approach
+ *
+ * */
+
+import java.util.Arrays;
+
+public class ReverseString {
+    public static void reverseString(char[] array) {
+        int head = 0;
+        int tail = array.length - 1;
+        while (head < tail) {
+            char temp = array[head];
+            array[head++] = array[tail];
+            array[tail--] = temp;
+        }
+    }
+
+    public static void main(String[] args) {
+        char example1[] = {'h', 'e', 'l', 'l', 'o'};
+        String result1 = "olleh";
+        System.out.println("Test 1");
+        System.out.println("Before: " + Arrays.toString(example1).replace("[", "").replace("]", "").replace(", ", ""));
+        reverseString(example1);
+        System.out.println("After: " + Arrays.toString(example1).replace("[", "").replace("]", "").replace(", ", ""));
+        System.out.println("Result: " + result1.equals(Arrays.toString(example1).replace("[", "").replace("]", "").replace(", ", "")));
+
+        char example2[] = {'H', 'a', 'n', 'n', 'a', 'h'};
+        String result2 = "hannaH";
+        System.out.println("Test 2");
+        System.out.println("Before: " + Arrays.toString(example2).replace("[", "").replace("]", "").replace(", ", ""));
+        reverseString(example2);
+        System.out.println("After: " + Arrays.toString(example2).replace("[", "").replace("]", "").replace(", ", ""));
+        System.out.println("Result: " + result2.equals(Arrays.toString(example2).replace("[", "").replace("]", "").replace(", ", "")));
+    }
+}

src/main/scala/com/kishan/scala/leetcode/juneChallenges/reverseString.scala

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+package com.kishan.scala.leetcode.juneChallenges
+
+/*
+- Write a function that reverses a string. The input string is given as an array of characters char[].
+- Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
+- You may assume all the characters consist of printable ascii characters.
+*/
+
+/*
+Examples:
+
+Input: ["h","e","l","l","o"]
+Output: ["o","l","l","e","h"]
+
+Input: ["H","a","n","n","a","h"]
+Output: ["h","a","n","n","a","H"]
+
+*/
+
+/*
+* Space complexity: O(1)
+* Time complexity: O(n/2)
+* */
+
+import scala.util.control.Breaks
+
+object reverseString {
+
+  def main(args: Array[String]): Unit = {
+    var example1: Array[Char] = Array('h', 'e', 'l', 'l', 'o')
+    var result1: String = "olleh"
+    println("Test 1")
+    println(s"Before: ${example1.mkString("")}")
+    reverseString(example1)
+    println(s"After: ${example1.mkString("")}")
+    println(s"Result: ${result1 == example1.mkString("")}")
+
+    var example2: Array[Char] = Array('H', 'a', 'n', 'n', 'a', 'h')
+    var result2: String = "hannaH"
+    println("Test 2")
+    println(s"Before: ${example2.mkString("")}")
+    reverseString(example2)
+    println(s"After: ${example2.mkString("")}")
+    println(s"Result: ${result2 == example2.mkString("")}")
+
+  }
+
+  def reverseString(s: Array[Char]): Unit = {
+    val length = s.length
+    val breaks = new Breaks()
+    breaks.breakable {
+      for (i <- 0 until length) {
+        val temp = s(i)
+        s(i) = s(length - 1 - i)
+        s(length - 1 - i) = temp
+        if (i == length / 2 - 1) {
+          breaks.break()
+        }
+      }
+    }
+  }
+}