Created LeetCode73 Set Matrix Zeros (Medium) #369

LeetCode Problems/_73_SetMatrixZeros.java

@@ -0,0 +1,52 @@
+package githubpr;
+
+import java.util.Arrays;
+
+/*
+time n2
+space constant (changing in place)
+ */
+public class _73_SetMatrixZeros {
+    public void setZeroes(int[][] matrix) {
+        matrixZeros(matrix);
+    }
+    public void matrixZeros(int[][] arr){
+        boolean firstCol=false,firstRow=false;
+
+        //Step 1 : check for zeros and mark in the first row/col
+        for(int i=0;i<arr.length;i++){
+            for (int j=0;j<arr[0].length;j++){
+                if(arr[i][j]==0){
+                    if (j==0) firstCol=true;
+                    if (i==0) firstRow=true;
+                    arr[i][0]=0;
+                    arr[0][j]=0;
+                }
+            }
+        }
+
+        //Step 2 : make rows and cols zeros if they have a zero, except first row/col
+        for(int i=1;i<arr.length;i++){
+            for(int j=1;j<arr[0].length;j++){
+                if(arr[i][0]==0 || arr[0][j]==0){
+                    arr[i][j]=0;
+                }
+            }
+        }
+
+        //Step 3 : making the firstrow and firstcol zero if required
+
+        //atleast one element is zero in the first row :- therefore making all zero
+        if(firstRow){
+            Arrays.fill(arr[0], 0);
+
+        }
+
+        //atleast one element is zero in the first col :- therefore making all zero
+        if(firstCol){
+            for(int i=0;i<arr.length;i++){
+                arr[i][0]=0;
+            }
+        }
+    }
+}