add 3240

Author: fishercoder1534

Diff for: paginated_contents/algorithms/4th_thousand/README.md

@@ -1,6 +1,7 @@
 | #    | Title                                                                                                                                                               | Solutions                                                                                                                         | Video                                                                         | Difficulty | Tag                                                                  
 |------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------|------------|----------------------------------------------------------------------
 | 3241 | [Time Taken to Mark All Nodes](https://leetcode.com/problems/time-taken-to-mark-all-nodes/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3241.java) |                                                                               | Hard       |
+| 3240 | [Minimum Number of Flips to Make Binary Grid Palindromic II](https://leetcode.com/problems/minimum-number-of-flips-to-make-binary-grid-palindromic-ii/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3240.java) |                                                                               | Medium     |
 | 3239 | [Minimum Number of Flips to Make Binary Grid Palindromic I](https://leetcode.com/problems/minimum-number-of-flips-to-make-binary-grid-palindromic-i/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3239.java) |                                                                               | Easy       |
 | 3238 | [Find the Number of Winning Players](https://leetcode.com/problems/find-the-number-of-winning-players/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3238.java) |                                                                               | Easy       |
 | 3237 | [Alt and Tab Simulation](https://leetcode.com/problems/alt-and-tab-simulation/)                                                                 | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/fourththousand/_3237.java) |                                                                               | Medium     | 

Diff for: src/main/java/com/fishercoder/solutions/fourththousand/_3240.java

@@ -0,0 +1,78 @@
+package com.fishercoder.solutions.fourththousand;
+
+public class _3240 {
+    public static class Solution1 {
+        /**
+         * Credit: https://leetcode.com/problems/minimum-number-of-flips-to-make-binary-grid-palindromic-ii/solutions/5580937/java-o-m-n/
+         */
+        public int minFlips(int[][] grid) {
+            int m = grid.length;
+            int n = grid[0].length;
+            int ans = 0;
+            for (int i = 0; i < m / 2; i++) {
+                for (int j = 0; j < n / 2; j++) {
+                    int cnt = 0;
+                    cnt += grid[i][j];
+                    cnt += grid[m - i - 1][j];
+                    cnt += grid[i][n - j - 1];
+                    cnt += grid[m - i - 1][n - j - 1];
+                    ans += Math.min(cnt, 4 - cnt);
+                }
+            }
+            int diff = 0;
+            int p0 = 0;
+            int p1 = 0;
+            //process if there's odd number of rows
+            if (m % 2 == 1) {
+                for (int j = 0; j < n / 2; j++) {
+                    if (grid[m / 2][j] != grid[m / 2][n - j - 1]) {
+                        diff++;
+                    } else {
+                        if (grid[m / 2][j] == 0) {
+                            p0++;
+                        } else {
+                            p1++;
+                        }
+                    }
+                }
+            }
+            //process if there's odd number of columns
+            if (n % 2 == 1) {
+                for (int i = 0; i < m / 2; i++) {
+                    if (grid[i][n / 2] != grid[m - i - 1][n / 2]) {
+                        diff++;
+                    } else {
+                        if (grid[i][n / 2] == 0) {
+                            p0++;
+                        } else {
+                            p1++;
+                        }
+                    }
+                }
+            }
+
+            if (m % 2 == 1 && n % 2 == 1) {
+                if (grid[m / 2][n / 2] == 1) {
+                    ans++;
+                }
+            }
+
+            int ans1;
+            if (diff % 2 == p1 % 2) {
+                ans1 = diff;
+            } else {
+                if (diff % 2 == 0) {
+                    if (diff == 0) {
+                        ans1 = 2;
+                    } else {
+                        ans1 = diff;
+                    }
+                } else {
+                    ans1 = diff;
+                }
+            }
+
+            return ans + ans1;
+        }
+    }
+}

Diff for: src/test/java/com/fishercoder/fourththousand/_3240Test.java

@@ -0,0 +1,23 @@
+package com.fishercoder.fourththousand;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions.fourththousand._3240;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class _3240Test {
+    private static _3240.Solution1 solution1;
+
+    @BeforeEach
+    public void setup() {
+        solution1 = new _3240.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(3, solution1.minFlips(CommonUtils
+                .convertLeetCodeIrregularLengths2DArrayInputIntoJavaArray("[1,0,0],[0,1,0],[0,0,1]")));
+    }
+}