Update Maximum Size Rectangle with Binary.java

Author: py3-coder

Stack_Interview Problem/Maximum Size Rectangle with Binary.java

@@ -92,3 +92,107 @@ public static int[] nsr(int arr[],int n){
 		return right;
 	}
 }
+
+//Leet Code  SOln: 
+class Solution {
+    public int maximalRectangle(char[][] matrix) {
+        int n=matrix.length;
+        int m=matrix[0].length;
+        int[][] mat = new int[n][m];
+        for(int i=0;i<n;i++){
+            for(int j=0;j<m;j++){
+                if(matrix[i][j]=='0'){
+                    mat[i][j]=0;
+                }else{
+                    mat[i][j]=1;
+                }
+            }
+        }
+        return maximalAreaOfSubMatrixOfAll1(mat,n,m);
+        
+    }
+    public static int maximalAreaOfSubMatrixOfAll1(int[][] mat, int n, int m) {
+		//Lets Play with Stack :: MAH Problem :: break into 1-D array::
+		int area=0;
+		int temp[] = new int[m];
+		for(int j=0;j<m;j++){
+				temp[j] =mat[0][j];
+		}
+		
+		area = MAH(temp, m);
+		for(int i=1;i<n;i++){
+			int maxi=0;
+			for(int j=0;j<m;j++){
+				if(mat[i][j]==0){
+					temp[j]=0;
+				}else{
+					temp[j] =temp[j]+mat[i][j];
+				}
+			}
+			//System.out.println();
+			maxi =MAH(temp, m);
+			//System.out.print(maxi+" ");
+			area =Math.max(maxi,area);
+		}
+		return area;
+
+	}
+	public static int MAH(int arr[] ,int n){
+		int[] left =nsl(arr, n);
+		int[] right =nsr(arr, n);
+		int width=0;
+		int area=0;
+		for(int i=0;i<n;i++){
+			width =right[i]-left[i]-1;
+			area=Math.max(width*arr[i],area);
+		}
+		return area;
+		 
+	}
+	public static int[] nsl(int arr[],int n){
+		int[] left =new int[n];
+		Stack<Integer> st = new Stack<>();
+
+		for(int i=0;i<n;i++){
+			if(st.isEmpty()){
+				left[i] =-1;
+			}else if(arr[st.peek()]<arr[i]){
+				left[i] =st.peek();
+			}else{
+				while(!st.isEmpty() && arr[st.peek()]>=arr[i]){
+					st.pop();
+				}
+				if(st.isEmpty()){
+					left[i] =-1;
+				}else{
+					left[i] =st.peek();
+				}
+			}
+			st.push(i);
+		}
+		return left;
+	}
+	public static int[] nsr(int arr[],int n){
+		int[] right =new int[n];
+		Stack<Integer> st = new Stack<>();
+
+		for(int i=n-1;i>=0;i--){
+			if(st.isEmpty()){
+				right[i] =n;
+			}else if(arr[st.peek()]<arr[i]){
+				right[i] =st.peek();
+			}else{
+				while(!st.isEmpty() && arr[st.peek()]>=arr[i]){
+					st.pop();
+				}
+				if(st.isEmpty()){
+					right[i] =n;
+				}else{
+					right[i] =st.peek();
+				}
+			}
+			st.push(i);
+		}
+		return right;
+	}
+}