题解 | #小乐乐改数字#

#include <stdio.h>

int main() {
    int a = 1;
    int b = 1;
    int c;
    long n;
    long sum = 0;
    scanf("%ld", &n);
    for(b = 1; b<9 ; b++ )
    {
        if(n/a>=0 && n/a<=9)
        {
            break;
        }
        else 
        {
            a*=10;
        }
	}
	//  printf("b为%d\n", b);   判断数的位数
    for(a = 1, c = 10; a<=b; a++)
    {
       if(((n%c)/(c/10))%2 != 0)   //从左到右依次检查是否为偶数
       {
			sum = sum+ (c/10);
	   }
	   	n = n-(n%c);                   //把检查完了的数去掉
		c=c*10;
    }
	printf("%d\n", sum);
    return 0;
}