add 2392

Author: fishercoder1534

Diff for: paginated_contents/algorithms/3rd_thousand/README.md

@@ -58,6 +58,7 @@
 | 2404 | [Most Frequent Even Element](https://leetcode.com/problems/most-frequent-even-element/)                                                                                                      | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2404.java)                                       || Easy                                 ||
 | 2399 | [Check Distances Between Same Letters](https://leetcode.com/problems/check-distances-between-same-letters/)                                                                                  | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2399.java)                                       || Medium                               ||
 | 2395 | [Find Subarrays With Equal Sum](https://leetcode.com/problems/find-subarrays-with-equal-sum/)                                                                                                | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2395.java)                                       || Easy                                 ||
+| 2392 | [Build a Matrix With Conditions](https://leetcode.com/problems/build-a-matrix-with-conditions/)                                                                                                | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2392.java)                                       || Hard                                 | Topological Sot, Graph, Matrix
 | 2389 | [Longest Subsequence With Limited Sum](https://leetcode.com/problems/longest-subsequence-with-limited-sum/)                                                                          | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2389.java)                                       || Easy                                 | 
 | 2385 | [Amount of Time for Binary Tree to Be Infected](https://leetcode.com/problems/amount-of-time-for-binary-tree-to-be-infected/)                                                                          | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2380.java)                                       || Medium                               | BFS                       
 | 2380 | [Time Needed to Rearrange a Binary String](https://leetcode.com/problems/time-needed-to-rearrange-a-binary-string/)                                                                          | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2380.java)                                       || Medium                               ||

Diff for: src/main/java/com/fishercoder/solutions/thirdthousand/_2392.java

@@ -0,0 +1,68 @@
+package com.fishercoder.solutions.thirdthousand;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+public class _2392 {
+    public static class Solution1 {
+        /**
+         * I figured out I needed to use Kahn's algorithm to topologically sort both rowConditions and colConditions,
+         * but unsure how to fill the matrix.
+         * https://leetcode.com/problems/build-a-matrix-with-conditions/editorial/ is brilliant as of how to build the matrix:
+         * using its slides to step through helps a lot!
+         */
+        public int[][] buildMatrix(int k, int[][] rowConditions, int[][] colConditions) {
+            int[] topologicallySortedRows = topologicalSort(rowConditions, k);
+            int[] topologicallySortedCols = topologicalSort(colConditions, k);
+            if (topologicallySortedRows.length == 0 || topologicallySortedCols.length == 0) {
+                return new int[][]{};
+            }
+            int[][] matrix = new int[k][k];
+            for (int i = 0; i < k; i++) {
+                for (int j = 0; j < k; j++) {
+                    if (topologicallySortedRows[i] == topologicallySortedCols[j]) {
+                        matrix[i][j] = topologicallySortedCols[j];
+                    }
+                }
+            }
+            return matrix;
+        }
+
+        private int[] topologicalSort(int[][] conditions, int k) {
+            List<Integer>[] adj = new ArrayList[k + 1];
+            for (int i = 0; i <= k; i++) {
+                adj[i] = new ArrayList<>();
+            }
+            int[] indegree = new int[k + 1];
+            int[] order = new int[k];
+            int index = 0;
+            for (int[] x : conditions) {
+                adj[x[0]].add(x[1]);
+                indegree[x[1]]++;
+            }
+            Queue<Integer> q = new LinkedList<>();
+            for (int i = 1; i <= k; i++) {
+                if (indegree[i] == 0) {
+                    q.offer(i);
+                }
+            }
+            while (!q.isEmpty()) {
+                Integer curr = q.poll();
+                order[index++] = curr;
+                k--;
+                for (int v : adj[curr]) {
+                    indegree[v]--;
+                    if (indegree[v] == 0) {
+                        q.offer(v);
+                    }
+                }
+            }
+            if (k != 0) {
+                return new int[0];
+            }
+            return order;
+        }
+    }
+}

Diff for: src/test/java/com/fishercoder/thirdthousand/_2392Test.java

@@ -0,0 +1,28 @@
+package com.fishercoder.thirdthousand;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions.thirdthousand._2392;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class _2392Test {
+    private static _2392.Solution1 solution1;
+
+    @BeforeEach
+    public void setup() {
+        solution1 = new _2392.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        CommonUtils.print2DIntArray(solution1.buildMatrix(
+                3,
+                new int[][]{
+                        {1, 2}, {3, 2}
+                },
+                new int[][]{
+                        {2, 1}, {3, 2}
+                }));
+    }
+
+}