#include<stdio.h>
#include<string.h>
int main()
{
    int n,i=0,j,temp=0;
    int a[99999];
    int b[20];
    scanf("%d",&b[0]);
    while(b[i]!=0)
    {
        i++;
        scanf("%d",&b[i]);
    }
    n=i;
    a[0]=0;
    a[1]=1;
    for(i=2;i<99999;i++)
    {
        if(i%2==0)
            a[i]=a[i/2];
        else
            a[i]=a[i/2]+a[i/2+1];
    }
    for(i=0;i<n;i++)
    {
        for(j=0;j<=b[i];j++)
        {
            if(a[j]>temp)
            {
                temp=a[j];
            }
        }
        printf("%d\n",temp);
    }
    fflush(stdin);
    getchar();
    return 0;
}

N can be as high as 99999; however you do int a[99999]; which only creates an array [0..99998].
Sigh, this counterintuitive syntax always creates errors like this.

thank you very much
but i change 99999 to 100000,it is still wrong ....sad...why...

Did you change it from 99999 to 100000 in BOTH places?
Also, you should do temp=0 before your for(j=0;j<=b[i];j++) or otherwise the maximum will remain the same as on previous request (you can try test 10, 5, 0 and it should give you 4 4 with your current code)

thank you!!!
it is temp that cause the wrong answer.
thanks!