SWUST OJ(963)

小偷的背包

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

int s, flag, n, *a; //主函数之外定义的变量为全局变量

void dfs(int index, int count, int * a)
{
    if(count == s)
    {
        flag = 1;
        return;
    }

    if (index > n)
    {
        return;
    }

    dfs(index + 1, count + a[index], a);
    dfs(index + 1, count, a);
}

int main(int argc, char const *argv[])
{
    scanf("%d",&s);
    scanf("%d",&n);

    a = (int*)malloc(n*sizeof(int));

    for (int i = 0; i < n; ++i)
    {
        scanf("%d",&a[i]);
    }

    dfs(0, 0, a);

    if (flag)
    {
        printf("yes!");
    }
    else
    {
        printf("no!");
    }
    return 0;
}