zigzag sequence

README.md

@@ -38,6 +38,8 @@ This repo register my evolution in the Cracking The Coding Interview book as I g
 
 [Tower Breakers](https://github.com/brendonmiranda/CrackingTheCodingInterview/blob/main/src/main/java/hackerRank/week2/TowerBreakers.java)
 
+[Find ZigZag Sequence]()
+
 # AWS Challenges
 
 [Review Score](https://github.com/brendonmiranda/CrackingTheCodingInterview/blob/main/src/main/java/aws/ReviewScore.java)

src/main/java/hackerRank/week2/FindZigZagSequence.java

@@ -0,0 +1,57 @@
+package hackerRank.week2;
+
+import java.util.Arrays;
+
+public class FindZigZagSequence {
+
+
+/*    public static void findZigZagSequence(int [] a, int n){
+        Arrays.sort(a);
+        int mid = (n + 1)/2;
+        int temp = a[mid];
+        a[mid] = a[n - 1];
+        a[n - 1] = temp;
+
+        int st = mid + 1;
+        int ed = n - 1;
+        while(st <= ed){
+            temp = a[st];
+            a[st] = a[ed];
+            a[ed] = temp;
+            st = st + 1;
+            ed = ed + 1;
+        }
+        for(int i = 0; i < n; i++){
+            if(i > 0) System.out.print(" ");
+            System.out.print(a[i]);
+        }
+        System.out.println();
+    }*/
+
+    // how it was above
+    // how it became below
+    // the trick below is that the first part of the method already give hints of what should become in the second part. be aware!
+    public static void findZigZagSequence(int [] a, int n){
+        Arrays.sort(a);
+        int mid = (n)/2; // changed here
+        int temp = a[mid];
+        a[mid] = a[n - 1];
+        a[n - 1] = temp;
+
+        int st = mid + 1;
+        int ed = n - 2; // here
+        while(st <= ed){
+            temp = a[st];
+            a[st] = a[ed];
+            a[ed] = temp;
+            st = st + 1;
+            ed = ed - 1; // here
+        }
+        for(int i = 0; i < n; i++){
+            if(i > 0) System.out.print(" ");
+            System.out.print(a[i]);
+        }
+        System.out.println();
+    }
+
+}