Add setmatrixzeros.java

Leetcode/setmatrixzeros.java

@@ -0,0 +1,72 @@
+import java.util.HashSet;
+
+public class setmatrixzero {
+    public static void main(String[]args)
+
+    {
+        int matrix[][] = { { 0, 1, 2, 0 }, { 3, 4, 5, 2}, { 1, 3, 1, 5} };
+        find(matrix);
+    }
+
+    private static void find(int[][] matrix) {
+        HashSet<Integer> zeroRows = new HashSet<>();
+        HashSet<Integer> zeroCols = new HashSet<>();
+        for (int i = 0; i < matrix.length; i++) {
+            for (int j = 0; j < matrix[i].length; j++) {
+                if (matrix[i][j] == 0) {
+                    zeroCols.add(j);
+                    zeroRows.add(i);
+                }
+            }
+        }
+
+        for (int i = 0; i < matrix.length; i++) {
+            for (int j = 0; j < matrix[i].length; j++) {
+
+                if (zeroRows.contains(i) || zeroCols.contains(j)) {
+                    matrix[i][j] = 0;
+                }
+
+
+
+
+
+            }
+        }
+        for (int i = 0; i < matrix.length; i++) {
+            for (int j = 0; j < matrix[i].length; j++) {
+                System.out.print(matrix[i][j]+" ");
+
+            }
+            System.out.println();
+        }
+    }
+}
+
+
+/*
+// this is best optimal appraoch using the boolean arrays 
+
+int m=matrix.length;
+        int n=matrix[0].length;
+
+        boolean[] forRows= new boolean[m];
+        boolean[] forCols= new boolean[n];
+
+        for(int i=0;i<m;i++){
+            for(int j=0;j<n;j++){
+                if(matrix[i][j]==0){
+                    forRows[i]=true;
+                    forCols[j]=true;
+                }
+            }
+        }//we marked the rows and cols with true
+
+        for(int i=0;i<m;i++){
+            for(int j=0;j<n;j++){
+                if(forRows[i] || forCols[j]){
+                    matrix[i][j]=0;
+                }
+            }
+        }
+*/