added question descriptions and additional programs and modified folder structure

Author: smv1999

2D Arrays/matrix_rotation.png

@@ -1,15 +1,15 @@
-// Finding common elements between two arrays in which the elements are distinct.
-// Eg:
+/*Finding common elements between two arrays in which the elements are distinct.
+Eg:
 
-// 1 2 3 4 5 12 8
-// 6 7 3 4 2 9  11
+1 2 3 4 5 12 8
+6 7 3 4 2 9  11
 
-// 1 2 3 4 5 8 12
-// 2 3 4 6 7 9 11
-
-// O/P:
-// 2 3 4 
+1 2 3 4 5 8 12
+2 3 4 6 7 9 11
 
+O/P:
+2 3 4 
+*/
 #include<iostream>
 #include<vector>
 #include<algorithm>

2D Arrays/matrix_spiral .png

@@ -1,3 +1,15 @@
+/*Finding common elements between two arrays in which the elements are distinct.
+Eg:
+
+1 2 3 4 5 12 8
+6 7 3 4 2 9  11
+
+1 2 3 4 5 8 12
+2 3 4 6 7 9 11
+
+O/P:
+2 3 4 
+*/
 #include<algorithm>
 #include<iostream>
 #include<vector>

Arrays/CommonElements.cpp

@@ -1,3 +1,13 @@
+/*
+Given an array arr of N integers. Find the contiguous sub-array with maximum sum.
+
+For Example:
+
+Input:
+N = 5
+arr[] = {1,2,3,-2,5}
+Output: 9
+*/
 #include<stdio.h>
 #include<limits.h>
 

Arrays/CommonElementsOptimal.cpp

@@ -1,74 +1,77 @@
-#include<stdio.h>
+/*
+The eight queens problem is the problem of placing eight queens on an 8×8 chessboard such that none of them attack one another 
+(no two are in the same row, column, or diagonal). More generally, the n queens problem places n queens on an n×n chessboard.
+*/
+#include <stdio.h>
 void solutionFinder(int tot_queens);
-void NQueenSolver(int queenPositions[],int tot_queens,int queenNum);
-int isSafe(int queenPositions[],int tot_queens,int choice,int queenNum);
+void NQueenSolver(int queenPositions[], int tot_queens, int queenNum);
+int isSafe(int queenPositions[], int tot_queens, int choice, int queenNum);
 #define SAFE 1
 #define UNSAFE 0
-void printBoard(int queenPositions[],int tot_queens);
+void printBoard(int queenPositions[], int tot_queens);
 int main()
 {
     solutionFinder(8);
     return 0;
 }
 void solutionFinder(int tot_queens)
 {
-   int queenPositions[tot_queens];
-   int ind;
-   for(ind=0; ind< tot_queens; ind++)
-    queenPositions[ind]=-1;//no queens placed at start
-    NQueenSolver(queenPositions,tot_queens,0);
-
+    int queenPositions[tot_queens];
+    int ind;
+    for (ind = 0; ind < tot_queens; ind++)
+        queenPositions[ind] = -1; //no queens placed at start
+    NQueenSolver(queenPositions, tot_queens, 0);
 }
-void NQueenSolver(int queenPositions[],int tot_queens,int queenNum)
+void NQueenSolver(int queenPositions[], int tot_queens, int queenNum)
 {
     //choices are 0 to tot_queens-1
     int choice;
-    if(tot_queens==queenNum)//
+    if (tot_queens == queenNum) //
     {
-       printBoard(queenPositions,tot_queens);
-       getch();
-       return;
+        printBoard(queenPositions, tot_queens);
+        getch();
+        return;
     }
-    for(choice=0;choice<tot_queens;choice++)
+    for (choice = 0; choice < tot_queens; choice++)
     {
-        if(isSafe(queenPositions,tot_queens,choice,queenNum)==SAFE)
+        if (isSafe(queenPositions, tot_queens, choice, queenNum) == SAFE)
         {
             //do certain things
-            queenPositions[queenNum]=choice;
-            NQueenSolver(queenPositions,tot_queens,queenNum+1);
-           //undo
-            queenPositions[queenNum]=-1;
+            queenPositions[queenNum] = choice;
+            NQueenSolver(queenPositions, tot_queens, queenNum + 1);
+            //undo
+            queenPositions[queenNum] = -1;
         }
     }
 }
-int isSafe(int queenPositions[],int tot_queens,int choice,int queenNum)
+int isSafe(int queenPositions[], int tot_queens, int choice, int queenNum)
 {
-    int row,col;
- //left top
- for(row=queenNum-1,col=choice-1;row>=0 && col>=0 ;row--,col--)
-    if(queenPositions[row]==col)
-        return UNSAFE;
- //top
- for(row=queenNum-1,col=choice;row>=0  ;row--)
-    if(queenPositions[row]==col)
-        return UNSAFE;
- //right top
-  for(row=queenNum-1,col=choice+1;row>=0 && col<tot_queens ;row--,col++)
-    if(queenPositions[row]==col)
-        return UNSAFE;
- return SAFE;
+    int row, col;
+    //left top
+    for (row = queenNum - 1, col = choice - 1; row >= 0 && col >= 0; row--, col--)
+        if (queenPositions[row] == col)
+            return UNSAFE;
+    //top
+    for (row = queenNum - 1, col = choice; row >= 0; row--)
+        if (queenPositions[row] == col)
+            return UNSAFE;
+    //right top
+    for (row = queenNum - 1, col = choice + 1; row >= 0 && col < tot_queens; row--, col++)
+        if (queenPositions[row] == col)
+            return UNSAFE;
+    return SAFE;
 }
-void printBoard(int queenPositions[],int tot_queens)
+void printBoard(int queenPositions[], int tot_queens)
 {
- int row,col;
- for(printf("\n"),row=0;row<tot_queens;row++,printf("\n"))
- {
-     for(col= 0 ;col< tot_queens;col++)
-     {
-         if(queenPositions[row]==col)
-            printf(" Q ");
-         else
-            printf(" - ");
-     }
- }
+    int row, col;
+    for (printf("\n"), row = 0; row < tot_queens; row++, printf("\n"))
+    {
+        for (col = 0; col < tot_queens; col++)
+        {
+            if (queenPositions[row] == col)
+                printf(" Q ");
+            else
+                printf(" - ");
+        }
+    }
 }

Arrays/kadane's_algorithm.c

@@ -1,3 +1,7 @@
+/*
+An SLL is a type of linked list in which each node consists of only two fields viz., data field and the address field.
+The address field is a pointer containing the address of the next node in the list.
+*/
 #include<iostream>
 
 using namespace std;

Backtracking/eightQueen.c

@@ -1,3 +1,7 @@
+/*
+Given an expression string exp, write a program to examine whether the pairs and the orders of “{“, “}”, 
+“(“, “)”, “[“, “]” are correct in exp.
+*/
 #include <bits/stdc++.h>
 using namespace std;
 bool isBalanced(string);