NKnight Problem Java Code Added

Java_Programs_for_beginners/NKnightProblem.java

@@ -0,0 +1,121 @@
+
+import java.util.Scanner;
+
+public class NKnightProblem {
+
+ private static Scanner sc;
+
+ public static void main(String[] args) {
+ sc = new Scanner(System.in);
+ int n = sc.nextInt();
+
+ boolean board[][] = new boolean[3][4];
+
+ int c = allc(0, 0, 0, board);
+ System.out.println(c);
+ all(0,0,0, "", board);
+
+ }
+
+ public static int allc(int row, int col, int kpsf,boolean v[][]) {
+ if (kpsf == v.length) { //knight placed so far
+ //System.out.print(ans + " ");
+ return 1;
+ }
+
+ int count = 0;
+
+ for (int c = col; c < v[0].length; c++) {
+ if (issafe(row, c, v)) {
+
+ v[row][c] = true;
+
+ count = count + allc(row, c + 1, kpsf + 1, v);
+ v[row][c] = false;
+ }
+
+ }
+
+ for (int r = row + 1; r < v.length; r++) {
+ for (int c = 0; c < v[0].length; c++) {
+ if (issafe(r, c, v)) {
+
+ v[r][c] = true;
+ count = count + allc(r, c + 1, kpsf + 1,v);
+ v[r][c] = false;
+ }
+
+ }
+ }
+ return count;
+
+ }
+
+ public static void all(int row, int col, int kpsf,String ans, boolean v[][]) {
+ if (kpsf == v.length) {
+
+ System.out.println(ans + " ");
+ return ;
+ }
+
+
+
+ for (int c = col; c < v[0].length; c++) {
+ if (issafe(row, c, v)) {
+
+ v[row][c] = true;
+
+ all(row, c + 1, kpsf + 1, ans + "{" + row + "-" + c + "}" + " ", v);
+ v[row][c] = false;
+ }
+
+ }
+
+ for (int r = row + 1; r < v.length; r++) {
+ for (int c = 0; c < v[0].length; c++) {
+ if (issafe(r, c, v)) {
+
+ v[r][c] = true;
+ all(r, c + 1, kpsf + 1, ans + "{" + r + "-" + c + "}" + " ",v);
+ v[r][c] = false;
+ }
+
+ }
+ }
+
+
+ }
+
+
+ public static boolean issafe(int row, int col, boolean v[][]) {
+
+ if (v[row][col])
+ return false;
+
+ int c = col;
+ int r = row - 2;
+ if (r >= 0 && c + 1 < v.length) {
+ if (v[r][c + 1])
+ return false;
+ }
+ if (r >= 0 && c - 1 >= 0) {
+ if (v[r][c - 1])
+ return false;
+ }
+ r = row - 1;
+ c = col;
+ if (r >= 0 && c - 2 >= 0) {
+ if (v[r][c - 2])
+ return false;
+ }
+ if (r >= 0 && c + 2 < v.length) {
+ if (v[r][c + 2])
+ return false;
+ }
+
+
+
+ return true;
+ }
+
+}