Add day 24

README.md

@@ -47,6 +47,7 @@ Read [CONTRIBUTING.md](./CONTRIBUTING.md) for contribution guidelines.
 21. [Day 21 -- Pair Sum N and Max Subarray Sum](./day21) -- [http://codetoexpress.tech/dc/day21/](http://codetoexpress.tech/dc/day21/)
 22. [Day 22 -- Common Elements Search](./day22) -- [http://codetoexpress.tech/dc/day22/](http://codetoexpress.tech/dc/day22/)
 23. [Day 23 -- Combination Sum](./day23) -- [http://codetoexpress.tech/dc/day23/](http://codetoexpress.tech/dc/day23/)
+24. [Day 24 -- Array Circular Rotation](./day24) -- [http://codetoexpress.tech/dc/day24/](http://codetoexpress.tech/dc/day24/)
 
 ## [More Problems](./BONUS/README.md)
 

day24/JavaScript/isRotation_madhav.js

@@ -0,0 +1,34 @@
+/**
+ * @author MadhavBahlMD
+ * @date 22/01/2019
+ * Method - Circular Search -- Time = O(n)
+ */
+
+function isRotation (arr1, arr2) {
+    let len1 = arr1.length,
+        len2 = arr2.length;
+
+    // return false if lengths are different
+    if (len1 !== len2)  return false;
+
+    // find position of first element of array2 in array 2
+    let isRotated = true,
+        pos = arr1.indexOf (arr2[0]);
+
+    // Return false if element not found
+    if (pos < 0)  return false;
+
+    // Check all the other numbers
+    for (let i=0; i<len1; i++) {
+        if (arr1[(pos+i)%len1] !== arr2[i]) {
+            isRotated = false;
+            break;
+        }
+    }
+
+    return isRotated;
+}
+
+console.log (isRotation ([1, 2, 3, 4, 5, 6, 7], [4, 5, 6, 7, 1, 2, 3]));  // true
+console.log (isRotation ([1, 2, 3, 4, 5, 6, 7], [7, 1, 2, 3]));  // false
+console.log (isRotation ([1, 2, 3, 4, 5, 6], [6, 5, 4, 3, 2, 1]));  // false 

day24/README.md

@@ -0,0 +1,61 @@
+![cover](./cover.png)
+
+# Day 24 - Array Series Part 7: Array Circular rotation
+
+**Question** -- Given 2 arrays (with no duplicate entries in any array), find whether one can be formed by rotating the other by 'n' elements. n < array length
+
+**Example**
+
+```
+input: arr1 = [1, 2, 3, 4, 5, 6, 7], arr2 = [4, 5, 6, 7, 1, 2, 3]
+output: true
+
+input: arr1 = [1, 2, 3, 4, 5, 6], arr2 = [6, 5, 4, 3, 2, 1]
+output: false
+
+input: arr1 = [1, 4, 2, 3, 6, 7, 9], arr2 = [5, 6, 2, 1, 9, 4]
+output: false
+```
+
+![ques](./ques.png)
+
+## JavaScript Implementation
+
+### [Solution](./JavaScript/isRotation_madhav.js)
+
+```js
+/**
+ * @author MadhavBahlMD
+ * @date 22/01/2019
+ * Method - Circular Search -- Time = O(n)
+ */
+
+function isRotation (arr1, arr2) {
+    let len1 = arr1.length,
+        len2 = arr2.length;
+
+    // return false if lengths are different
+    if (len1 !== len2)  return false;
+
+    // find position of first element of array2 in array 2
+    let isRotated = true,
+        pos = arr1.indexOf (arr2[0]);
+
+    // Return false if element not found
+    if (pos < 0)  return false;
+
+    // Check all the other numbers
+    for (let i=0; i<len1; i++) {
+        if (arr1[(pos+i)%len1] !== arr2[i]) {
+            isRotated = false;
+            break;
+        }
+    }
+
+    return isRotated;
+}
+
+console.log (isRotation ([1, 2, 3, 4, 5, 6, 7], [4, 5, 6, 7, 1, 2, 3]));  // true
+console.log (isRotation ([1, 2, 3, 4, 5, 6, 7], [7, 1, 2, 3]));  // false
+console.log (isRotation ([1, 2, 3, 4, 5, 6], [6, 5, 4, 3, 2, 1]));  // false 
+```