CODE:

#include 
#include 
#include    
#include      

using namespace std;

#define MAX_NUM 99999
#define MAX_WALK 9999

int main()
{
    	cout > num ;
            if(numMAX_NUM)
            {
            	cout > walk ;
            if(walkMAX_WALK)
            {
            	cout << "１から９９９９までの値を入力してください。\n";
                walk=-1;
            }
            else break;
        }
        
        double r_sum=0; //距離の合計
        srand((unsigned) time(NULL));
    
        for(int i=0; i < num ; i++)
        {
            int x=0;
            int y=0;
            
            for(int j=0; j < walk ; j++)
            {
                switch(rand()%4)
                {
                    case 0:
                        x++;
                        break;
                    case 1:
                        x--;
                        break;
                    case 2:
                        y++;
                        break;
                    case 3:
                        y--;
                        break;
                }
            }
            
            r_sum+=sqrt(double(x*x+y*y));
        }
        
    	cout << "平均距離は" << r_sum/num << "です。\n ";
    return 0;
}