UVALive - 3621 Power Calculus

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int MAXN = 1010;
const int INF = 10000007;

int arr[MAXN],num;

int dfs(int n,int step){
    if (num > step)
        return 0;
    if (arr[num] == n)
        return 1;
    if (arr[num] << (step-num) < n)
        return false;
    for (int i = 0; i <= num; i++){
        num++;
        arr[num] = arr[num-1] + arr[i];
        if (arr[num] <= 10000 && dfs(n,step))
            return true;
        arr[num] = arr[num-1] - arr[i];
        if (arr[num] > 0 && dfs(n,step))
            return 1;
        num--;
    }
    return 0;
}

int main(){
    int n;
    while (scanf("%d",&n) != EOF && n){
        int i;
        for (i = 0; ; i++){
            arr[num = 0] = 1;
            if (dfs(n,i))
                break;
        }
        printf("%d\n",i);
    }    
    return 0;
}