From be367c62124b1ab7b495a40c4b342248a957341d Mon Sep 17 00:00:00 2001
From: UvFlint <107190312+UvFlint@users.noreply.github.com>
Date: Fri, 17 Feb 2023 19:43:16 +0100
Subject: [PATCH] Create 2020b-96-Qs.java

answer for question 1 in sheelon 2020b-96.
---
 Exams/2020/2020b-96-Qs.java | 42 +++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 Exams/2020/2020b-96-Qs.java

diff --git a/Exams/2020/2020b-96-Qs.java b/Exams/2020/2020b-96-Qs.java
new file mode 100644
index 0000000..2311870
--- /dev/null
+++ b/Exams/2020/2020b-96-Qs.java
@@ -0,0 +1,42 @@
+
+public class 2020b96-Qs{
+
+  
+//q1 - maxSumKnight
+public static int maxSumKnight(int[][] mat){
+    boolean[][] visited = new boolean[mat.length][mat.length]; //make a boolean copy of mat to track visited cells
+    int first_value = mat[0][0]; //value of starting point
+	return maxSumKnight(mat,0,0,0, visited,first_value); //overload
+}
+  
+public static int maxSumKnight(int[][] mat, int i, int j, int sum, boolean[][] visited, int last_value){
+
+	if (i>mat.length-1 || j>mat[0].length-1 || i<0 || j<0) //if out of bounds
+		return Integer.MIN_VALUE;
+
+    int current_value = mat[i][j];
+    if (visited[i][j] || Math.abs(current_value-last_value)>1){ //check if a visited cell or if the difference between values is above 1 
+        return Integer.MIN_VALUE;
+    }
+
+	if (i==mat.length-1 && j==mat[0].length-1){ //if end of mat
+		return sum+mat[i][j];
+    }
+
+    visited[i][j] = true; //mark visited cell as true
+    last_value = mat[i][j];//current value to pass into the recursion
+  
+  //simplification of the knight moves - knight has 8 moves max. 2 north-west, 2 north-east, 2 south-west, 2 south-east.
+	int northWestPaths = Math.max(maxSumKnight(mat, i-1, j-2, sum+mat[i][j],visited, last_value), maxSumKnight(mat, i-2, j-1, sum+mat[i][j], visited, last_value));
+
+	int northEastPaths = Math.max(maxSumKnight(mat, i-2, j+1, sum+mat[i][j],visited, last_value), maxSumKnight(mat, i-1, j+2, sum+mat[i][j], visited, last_value));
+
+	int southWestPaths = Math.max(maxSumKnight(mat, i+1, j-2, sum+mat[i][j], visited, last_value), maxSumKnight(mat, i+2, j-1, sum+mat[i][j], visited, last_value));
+
+	int southEastPaths = Math.max(maxSumKnight(mat, i+2, j+1, sum+mat[i][j], visited, last_value), maxSumKnight(mat, i+1, j+2, sum+mat[i][j], visited, last_value));
+  
+  //find max sum between all paths
+	return Math.max(Math.max(northWestPaths, northEastPaths),Math.max(southWestPaths, southEastPaths));
+  }
+  // I am sure there is a way to do it without the boolean[][] visited. Happy for any suugestions. 
+}