added FillASpecialGrid

Author: abhishekghoshh

docs/recursion.md

@@ -28,6 +28,7 @@
 - [Generate Parentheses](src/com/problems/recursion/GenerateAllBalancedParenthesis.java)
 - [Print N-bit binary numbers having more 1s than 0s](src/com/problems/recursion/GenerateNBitBinaryNumberHavingMore1sInAllPrefixes.java)
 - [Subarrays with Sum k](src/com/problems/recursion/SubarraysWithSumK.java)
+- [Fill a Special Grid](src/com/problems/recursion/FillASpecialGrid.java)
 
 
 - [Print all subsequences/Power Set with unique elements](src/com/problems/recursion/PowerSet1.java)

docs/src/com/problems/recursion/FillASpecialGrid.java

@@ -0,0 +1,55 @@
+package com.problems.recursion;
+
+import com.util.PrintUtl;
+
+/*
+ * Problem links:
+ * https://leetcode.com/problems/fill-a-special-grid/description/
+ *
+ * Solution link
+ *
+ * */
+public class FillASpecialGrid {
+    public static void main(String[] args) {
+        type1();
+        type2();
+    }
+
+    // recursive way
+    private static void type2() {
+        int N = 2;
+        int[][] ans = specialGrid1(N);
+        PrintUtl.print2D(ans);
+    }
+
+    public static int[][] specialGrid1(int N) {
+        if (N == 0) return new int[][]{new int[]{0}};
+        int n = 1 << N;
+        int[][] arr = new int[n][n];
+        int low = 0, high = (1 << 2 * N) - 1;
+        fill2(arr, low, high, 0, n - 1, 0, n - 1);
+        return arr;
+    }
+
+    private static void fill2(int[][] arr, int low, int high, int x1, int x2, int y1, int y2) {
+        int count = high - low + 1;
+        int d = (x2 - x1 + 1) / 2;
+        int q = count / 4;
+        if (count == 4) {
+            arr[x1][y2] = low;
+            arr[x2][y2] = low + 1;
+            arr[x2][y1] = low + 2;
+            arr[x1][y1] = high;
+        } else {
+            fill2(arr, low, low + q - 1, x1, x1 + d - 1, y1 + d, y2);
+            fill2(arr, low + q, low + 2 * q - 1, x1 + d, x2, y1 + d, y2);
+            fill2(arr, low + 2 * q, low + 3 * q - 1, x1 + d, x2, y1, y1 + d - 1);
+            fill2(arr, low + 3 * q, high, x1, x1 + d - 1, y1, y1 + d - 1);
+        }
+    }
+
+    // iterative way
+    private static void type1() {
+
+    }
+}

docs/src/com/problems/recursion/SubarraysWithSumK.java

@@ -5,7 +5,7 @@
 
 /*
  * Problem links:
- * https://www.codingninjas.com/studio/problems/subarrays-with-sum-%E2%80%98k'_6922076
+ * https://www.naukri.com/code360/problems/subarrays-with-sum-k_6922076
  * Solution link
  *
  * */