2115565_ac_15ms_32k.c

北大大牛代码 1240道题的原代码 超级权威

# include <stdio.h>
# include <math.h>
# include <string.h>
# include <stdlib.h>

void input()
{
	int i, no, mark, l;
	long n, r, ans;
	char num[25];

	while(scanf("%ld",&n)==1&&n)
	{
		no = mark = 0;
		ltoa(n,num,2);
		l = strlen(num);
		for(i = l-1; i > 0; i--)
		{
			if(num[i]=='1'&&num[i-1]=='0')
			{
				num[i-1] = '1';
				num[i] = '0';
				mark = 1;
				break;
			}
			else
				if(num[i]=='1')
				{
			    	no++;
			    	num[i] = '0';
				}
		}
		if(mark)
		{
			ans = (long)pow(2,no)-1;r = 1;
			for(i = l-1; i >= 0; i--)
			{
				ans += (num[i]-'0')*r;
				r *= 2;
			}
		}
		else
			ans = (long)pow(2,l)+(long)pow(2,no)-1;
		printf("%ld\n",ans);
	}
}

int main()
{
	input();
	return 1;
}