10进制转化为-2进制

例子：-13 =  1*1 +1*-2+1*4+0*8+1*16+1*-32   -2进制为110111

输入-13

输出：110111

代码： 只会用递归写，想不出什么好办法。

#include<stdio.h>

#include<stdlib.h>

#include<math.h>

int calresult(int *a, int start, int end,int data,int sum)

{
if(data == 0) return 1;
if(sum == 0)return 0;
int i;
for(i = start;i<end;i++)
{
int key = pow(-2,end-i-1);
a[i] = 1;
int result = calresult(a,i+1,end,data-key,sum-1);
if(result == 1) return result;
a[i] = 0;
}
return 0;

}

char *tentofu2(int n,int *num)

{
int a[32] = {0};
int i;
for(i=0;i<=32;i++)
{
int result = calresult(a,0,32,n,i);
if(result == 1)
{
break;
}
}

char *p = malloc(sizeof(char) * 33);
int j  =0;
i = 0;
while(a[i] == 0&&i<32) i++;
if(i == 32)
{
p[j++] = '0' + (a[i-1] -0);
p[j] = '\0';
}
else 
{
while(i<32)
{
p[j++] = '0' + (a[i++] -0);
}
}
*num = j;

return p;

}

int main()

{
int n;
scanf("%d",&n);
int num;

char *p = tentofu2(n,&num);
int i;

for(i = 0;i<=num;i++)
{
printf("%c",p[i]);
}
printf("\n");
free(p);

}