Grid Traversal

There is a rectangular grid of size m * n . Bob is in location ( x, y ) inside grid. He can move in 4 directions up, down, right and left. He will die if he steps outside of rectangular grid. Find the probability that bob is alive given initial position of bob as ( x, y ) and number of steps he moves as N. (Given that Bob moves only one step at a time).

#include<iostream>
using namespace std;
int main()
{
    void fun(int,int,int,int,float*,float*,int,int);
    int m,n,x,y,N;
    float a=0.0,b=0.0,*p=&a,*q=&b;
    cin>>m>>n>>x>>y>>N;
    fun(m,n,x,y,p,q,0,N);
    cout<<(*q)/((*q)+(*p));
}
void fun(int m,int n,int x,int y,float *p,float *q,int S,int N)
{    
    if(S==N && x>=0 && y>=0 && x<m && y<n)
    {
        (*q)++;
        return;
    }
    else if((S<=N) && (x<0 || y<0 || x>=m || y>=n))
    {
        (*p)++;
        return;
    }
    else
    {
        fun(m,n,x+1,y,p,q,S+1,N);
        fun(m,n,x-1,y,p,q,S+1,N);
        fun(m,n,x,y+1,p,q,S+1,N);
        fun(m,n,x,y-1,p,q,S+1,N);
    }
}

Excel column header generator

#include<iostream>
#include<string.h>
using namespace std;
int main()
{
        char out[27]={'Z','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y',0};
        char ans[100]={0};
        int t;
        cin>>t;
        while(t--)
        {
                int n;
                cin>>n;
                int j=0;
                while(n>0)
                {
                        int c=n%strlen(out);
                        //Using the remainder as the index of the character array.
                        ans[j]=out[c];
                        if(c==0)
                        {
                                n--;
                        }
                        n/=strlen(out);
                        j++;
                }
                //Reversing the answer string.
                for(int i=0;i<strlen(ans)/2;i++)
                {
                        char t=ans[i];
                        ans[i]=ans[strlen(ans)-i-1];
                        ans[strlen(ans)-i-1]=t;
                }
                cout<<ans<<endl;
        }
        return 0;
}

Sample Input: The first line is the number of test cases.
7
1
25
26
27
51
52
676

Sample Output:
A
Y
Z
AA
AY
AZ
YZ

C++ Program for Quicksort

#include<iostream>
using namespace std;
int main()
{
        int A[7]={3,6,1,2,7,5,4};
        void quicksort(int[],int,int);
        quicksort(A,0,6);
        for(int i=0;i<7;i++)
        {
                cout<<A[i]<<" ";
        }
        cout<<endl;         
        return 0; 
} 
void quicksort(int A[7],int low,int high) 
{         
        if(low>=high)
        {
                return;
        }
        int p=A[low];
        int i=low+1;
        int j=high;
        while(j>=i)
        {
                while(A[i]<=p)
                {
                         i++;                 
                }
                while(A[j]>p)
                {
                        j--;
                }
                if(j>i)
                {
                        int t=A[i];
                        A[i]=A[j];
                        A[j]=t;
                }
        }
        int t=A[j];
        A[j]=A[low];
        A[low]=t;
        quicksort(A,low,j-1);
        quicksort(A,j+1,high);
}

C++ Program for Mergesort

#include<iostream>
using namespace std;
int main()
{
        void mergesort(int[],int,int);
        int A[7]={1,2,5,3,7,6,4};
        int low=0,high=6;
        mergesort(A,0,6);
        for(int i=low;i<=high;i++)
        {
                cout<<A[i]<<" ";
        }
        cout<<endl;
        return 0;
}
void mergesort(int A[7],int low,int high)
{
        if(low==high)
        {
                return;
        }
        int mid=(low+high)/2;
        mergesort(A,low,mid);
        mergesort(A,mid+1,high);
        int a=low;
        int b=mid+1;
        int B[100],j=0;
        while(a<=mid && b<=high)
        {
                if(A[a]<A[b])
                {
                        B[j]=A[a];
                        j++;
                        a++;
                }
                else if(A[b]<A[a])
                {
                        B[j]=A[b];
                        j++;
                        b++;
                }
        }
        while(a<=mid)
        {
                B[j]=A[a];
                j++;
                a++;
        }
        while(b<=high)
        {
                B[j]=A[b];
                j++;
                b++;
        }
        int k=0;
        for(int i=low;i<=high;i++)
        {
                A[i]=B[k];
                k++;
        }
}