递归的两个例程

/*
#include <iostream>
using namespace std;
void countdown(int n);
int main()
{
    countdown(4);
    return 0;
}
void countdown(int n)
{
    cout << "Counting down ..." << n << endl;
    if(n>0)
        countdown(n-1);
    cout << n << ": Kaboom!\n";
}
*/
/*
Counting down ...4
Counting down ...3
Counting down ...2
Counting down ...1
Counting down ...0
0: Kaboom!
1: Kaboom!
2: Kaboom!
3: Kaboom!
4: Kaboom!

Process returned 0 (0x0)   execution time : 0.266 s
Press any key to continue.

*/
#include<iostream>
using namespace std;
const int Len = 66;
const int Divs = 6;
void subdivide(char ar[], int low, int high, int level);
int main()
{
    char ruler[Len];
    int i;
    for(i=1; i<Len-2; i++)
        ruler[i] = ' ';
    ruler[Len-1] = '\0';
    int max = Len-2;
    int min = 0;
    ruler[min] = ruler[max] = '|';
    cout << ruler << endl;
    for(i=1; i<=Divs; i++)
    {
        subdivide(ruler, min, max, i);
        cout << ruler << endl;
        for(int j=1;j<Len-2; j++)
            ruler[j] = ' ';
    }
    return 0;
}
void subdivide(char ar[], int low, int high, int level)
{
    if(level == 0)
        return;
    int mid = (high+low)/2;
    ar[mid] = '|';
    subdivide(ar, low, mid, level-1);
    subdivide(ar, mid, high, level-1);
}
/*
|                                                               |
|                               |                               |
|               |               |               |               |
|       |       |       |       |       |       |       |       |
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

Process returned 0 (0x0)   execution time : 0.078 s
Press any key to continue.

*/