Merge pull request #631 from Jayshree-2111/DevIncept1

N_Queens Problem using C

Author: Saviour1001

Arrays/Rotate Array (LeetCode)-Top Interview Que-Easy Level.cpp

@@ -0,0 +1,27 @@
+class Solution //Solution Class
+{
+    public:
+        void rotate(vector<int>& nums, int k) //function for shifting the elements
+        {
+            int n = nums.size(); //assign size of array
+            int start = n - k % n; //starting from first element
+            int remainder = k % n; //to move to next index
+            vector<int> v(n);
+            
+            for(int i = 0; i < remainder; i++) //shifting the index
+             {
+                v[i] = nums[i + start];
+             }
+            
+            for(int i = 0; i < start; i++) //shifting the index
+            {
+                v[i + remainder] = nums[i];
+            }
+            
+            for(int i = 0; i < n; i++) //for shifting elements
+            {
+                nums[i] = v[i];
+            }
+        }
+};
+

Backtracking/N_Queens Problem.c

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+/* The N Queen is the problem of placing N chess queens on an 
+N×N chessboard so that no two queens attack each other.
+
+Language Used: C language
+
+Output: The expected output is a binary matrix which has numbers 
+        for the blocks where queens are placed. 
+        
+For example, following is the output matrix for above 4 queen solution.
+OUTPUT FOR 4 Queens: { 2,  4,  1,  3}
+              		 { 3,  1,  4,  2}
+*/
+#include<stdio.h>
+#include<stdlib.h>
+#include<conio.h>
+#include<math.h>
+
+int place(int r,int c,int x[])//function gives resultant appropriate place for the queen 
+{
+    int i;
+    for(i=1; i<r; i++)
+    {
+        if(x[i]==c||(abs(x[i]-c)==abs(i-r)))
+            return 0;
+    }
+    return 1;
+}
+
+void NQueen(int r,int n,int x[]) //function for checking the places of the queen so that one queen would not attack other
+{
+    int c,i;
+    for(c=1; c<=n; c++)
+    {
+        if(place(r,c,x))
+        {
+            x[r]=c;
+            if(r==n)
+            {
+                printf("{");
+                for(i=1; i<=n; i++) 
+                    printf(" %d",x[i]);
+                printf(" }\n");
+            }
+            else
+                NQueen(r+1,n,x);
+        }
+    }
+}
+int main()
+{
+    int n,i,j;
+    int x[50];
+    printf("\nEnter the no. of Queens: ");
+    scanf("%d",&n);
+    printf("\nResultant Places of Queens: \n");
+    NQueen(1,n,x);
+}