backtracking

Coding/Java/backtracking_ratMaze.java

@@ -0,0 +1,73 @@
+
+import java.util.*;
+
+class Rat{
+    public static void main(String args[]){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+
+        while(t-- > 0){
+            int n = sc.nextInt();
+            int[][] a = new int[n][n];
+            for(int i=0;i<n;i++){
+               for(int j=0;j<n;j++){
+                   a[i][j]=sc.nextInt();
+               }
+            }
+
+            GFG g = new GFG();
+            ArrayList<String> res = g.printPath(a,n);
+            if(res.size()>0){
+               for(int i=0;i<res.size();i++){
+                   System.out.print(res.get(i)+" ");
+               }
+               System.out.println();
+             }
+               else{
+                  System.out.println(-1);
+               }
+            }
+        }
+    }
+
+class GfG {
+     ArrayList<String> list;
+    public ArrayList<String> printPath(int[][] m, int n) {
+        boolean[][] vis=new boolean[n][n];
+
+        list = new ArrayList<>();
+        String path="";
+
+        ratMaze("",m,n,0,0,vis,path);
+
+        Collections.sort(list);
+        return list;
+    }
+
+     boolean isPosible(int[][]m ,int i, int j,int n,boolean[][] vis){
+        return i>=0 && j>=0 && i<n && j<n && m[i][j]==1 && vis[i][j]==false;
+    }
+
+    public void ratMaze(String direction,int[][] m,int n,int i,int j,boolean[][] vis,String path){
+        if(!isPosible(m,i,j,n,vis)) return;
+        if(i==n-1 && j==n-1){
+            path+=direction;
+            list.add(path);
+
+            path="";
+            return;
+        }
+
+        vis[i][j]=true;
+        path+=direction;
+        ratMaze("L",m,n,i,j-1,vis,path);
+        ratMaze("D",m,n,i+1,j,vis,path);
+        ratMaze("R",m,n,i,j+1,vis,path);
+        ratMaze("U",m,n,i-1,j,vis,path);
+
+        vis[i][j]=false;
+
+        return;
+
+    }
+}