Arrays-2 completed

Leetcode289.java

@@ -0,0 +1,61 @@
+class Solution {
+    // This method will count all the ones in the neighbouring indices
+    private int countOnes(int[][] board, int row, int col) {
+        int[][] ids = new int[][] { { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 }, { 0, 1 }, { 1, -1 }, { 1, 0 },
+                { 1, 1 } };
+        int count = 0;
+        for (int[] id : ids) {
+            int r = row + id[0];
+            int c = col + id[1];
+            if (r >= 0 && r < board.length && c >= 0 && c < board[0].length) {
+                if (board[r][c] == 1 || board[r][c] == 2) {
+                    count += 1;
+                }
+            }
+        }
+
+        return count;
+    }
+
+    public void gameOfLife(int[][] board) {
+        // 1 -> 2 -> 0 if < 2 1's
+        // 1 -> 1 -> 1 if =2,3 1's
+        // 1 -> 2 -> 0 if >3 1's
+        // 0 -> 3 -> 1 if =3 1's
+        int m = board.length;
+        int n = board[0].length;
+
+        for (int r = 0; r < m; r++) {
+            for (int c = 0; c < n; c++) {
+                int count = countOnes(board, r, c);
+                if (board[r][c] == 0 && count == 3) {
+                    board[r][c] = 3; // convert dead state to temp state (3) indicating it was in dead state earlier
+                                     // and needs to move to live state.
+
+                } else if (board[r][c] == 1) {
+                    if (count < 2 || count > 3) {
+                        board[r][c] = 2; // convert live state to temp state (2) indicating it was in live state earlier
+                                         // and needs to move to dead state.
+
+                    }
+                }
+
+            }
+            ;
+        }
+
+        // At this point the board matrix will have the temp state so we'll convert 2->0
+        // and 3->1
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                if (board[i][j] == 2) {
+                    board[i][j] = 0;
+                } else if (board[i][j] == 3) {
+                    board[i][j] = 1;
+                }
+
+            }
+        }
+
+    }
+}

Leetcode448.java

@@ -0,0 +1,28 @@
+// TC - O(n)
+// SC - O(1)
+class Solution {
+    public List<Integer> findDisappearedNumbers(int[] nums) {
+        List<Integer> res = new ArrayList<>();
+
+        for (int i = 0; i < nums.length; i++) {
+            int val = nums[i];
+            if (val < 0) {
+                val = val * (-1);
+            }
+            if (nums[val - 1] > 0) {
+                nums[val - 1] = -1 * nums[val - 1];
+            }
+
+        }
+
+        for (int i = 0; i < nums.length; i++) {
+            if (nums[i] > 0) {
+                res.add(i + 1);
+            }
+
+        }
+
+        return res;
+
+    }
+}