uva 574 Sum It Up

这一道题 ，我本以为按常规方法做，以为只要比较前一组输出就行，可后来调试发现，输出竟然与上上一组重复，所以我重新写了好思路形成的代码。

代码如下：

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#define TEST
using namespace std;

int sum1[13],sum2[13],sum3[13],sum4[13];
int n,t,d,flag;
void print_num();
void backtracking(int m);
bool cmp(int a,int b)
{
    return a > b;
}

void print_num(int m)
{

    int index = 1,f;
    flag = 0;
    for(int i = 0; i <= d; i++)
    {
        if(sum4[i] != 0)
        {
           f =sum4[i];

            while(f--){
                if(index) {printf("%d",sum2[i]); index = 0;}
            else printf("+%d",sum2[i]);
            }

        }

    }sum4[m] = 0;
    printf("\n");
}
void backtracking(int m)
{
    int f;
    if(t <= 0)
    {
        if(t == 0)
            print_num(m);
        return ;
    }
    else if(m <=d)
    {

     f = sum3[m];
     f++;
    do
    {

         f --;

        sum4[m] = f;
        t -=sum2[m]*f;
        backtracking(m+1);
         t +=sum2[m]*f;
        sum4[m] = 0;

    }while(f);

    }
    return ;
}
int main()
{
    #ifdef TEST
    freopen("in.txt","r",stdin);
    freopen("out.text","w",stdout);
    #endif // TEST
    int i;
    while(~scanf("%d",&t))
    {
        d = 0;
        scanf("%d",&n);
        if(n == 0) break;
        for(i= 0;i < n;i ++)
            scanf("%d",&sum1[i]);
        sort(sum1,sum1+n,cmp);
        memset(sum2,0,sizeof(sum2));
        memset(sum3,0,sizeof(sum3));// 注意不能memset 1;
        memset(sum4,0,sizeof(sum4));
        sum2[0] = sum1[0];
        sum3[0] ++;
        for(i = 1; i < n; i ++)
        {
            if(sum1[i-1] == sum1[i])
            {
                sum3[d] ++;
            }
            else{
                sum2[++d] = sum1[i];
                sum3[d] ++;
            }
        }

        flag = 1;
        printf("Sums of %d:\n",t);
        backtracking(0);
        if(flag) printf("NONE\n");
    }
}