HDU_1709 The Balence (生成函数)

　　/*用砝码秤重量，按照左物右码的话，砝码的值可以取负。因为砝码最多就一个，
所以不许要一般模板里的k 那一重循环，直接去砝码个数为0， 1的两种情况就行。开
始把重量取负时那种情况想错了，WA了好几次。。。T_T*/

//My Code:

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

const int N = 10007;

int c1[N], c2[N];
int val[107];

int main() {
    //freopen("data.in", "r", stdin);

    int n, s, i, j, tmp, cnt;
    while(~scanf("%d", &n)) {
        memset(c1, 0, sizeof(c1));
        memset(c2, 0, sizeof(c2));
        memset(val, 0, sizeof(val));

        for(s = 0, i = 1; i <= n; ++i) {
            scanf("%d", &val[i]);
            s += val[i];
        }
        c1[0] = 1; c1[val[1]] = 1;
        for(i = 2; i <= n; ++i) {
            for(j = 0; j + val[i] <= s; ++j) {
                if(c1[j] != 0) {
                    c2[j] += c1[j];
                    c2[j+val[i]] += c1[j];
　　　　　　　　　　　 tmp = j - val[i];   //这里WA了好几次。。。
                    tmp = tmp > 0 ? tmp : -1*tmp;
                    c2[tmp] += c1[j];
                }
            }
            for(j = 0; j <= s; ++j) {
                c1[j] = c2[j]; c2[j] = 0;
            }
        }
        for(cnt = 0, i = 0; i <= s; ++i) {
            if(!c1[i])    cnt++;
        }
        printf("%d\n", cnt);
        for(j = 0, i = 0; i <= s && j <= cnt; ++i) {
            if(!c1[i]) {
                printf("%d", i); ++j;
                if(j == cnt)    putchar('\n');
                else    putchar('');
            }
        }
    }
    return 0;
}