created a file named rankofMatrix and wrote code

rankofMatrix.java

@@ -0,0 +1,58 @@
+class Solution {
+
+    private int[] f;
+
+    public int[][] matrixRankTransform(int[][] matrix) {
+        int m = matrix.length;
+        int n = matrix[0].length;
+        int[][] ret = new int[m][n];
+        int[] row = new int[m];
+        int[] col = new int[n];
+        PriorityQueue<int[]> q = new PriorityQueue<>((a, b) -> a[0] - b[0]);
+        for (int i = 0; i < m; i++)
+            for (int j = 0; j < n; j++)
+                q.add(new int[]{matrix[i][j], i, j});
+        while (!q.isEmpty()) {
+            int target = q.peek()[0];
+            List<int[]> list = new ArrayList<>();
+            while (!q.isEmpty() && q.peek()[0] == target)
+                list.add(q.poll());
+            f = new int[n + m];
+            for (int i = 0; i < n + m; i++) f[i] = i;
+            for (int[] arr : list) {
+                int t1 = find(arr[1]);
+                int t2 = find(arr[2] + m);
+                if (t1 != t2)
+                    f[t1] = t2;
+            }
+            Map<Integer, List<int[]>> map = new HashMap<>();
+            for (int[] arr : list) {
+                int t = find(arr[1]);
+                if (!map.containsKey(t))
+                    map.put(t, new ArrayList<>());
+                map.get(find(arr[1])).add(arr);
+            }
+            //System.out.println(list.size());
+            for (List<int[]> group : map.values()) {
+                int rank = 0;
+                for (int[] arr : group) {
+                    int i = arr[1], j = arr[2];
+                    rank = Math.max(rank, Math.max(row[i], col[j]) + 1);
+                }
+                for (int[] arr : group) {
+                    int i = arr[1], j = arr[2];
+                    ret[i][j] = rank;
+                    row[i] = Math.max(row[i], rank);
+                    col[j] = Math.max(col[j], rank);
+                }
+            }
+        }
+        return ret;
+    }
+
+    private int find(int x) {
+        if (f[x] == x)
+            return f[x];
+        return f[x] = find(f[x]);
+    }
+}