HDU_2152 Fruit(生成函数)

　　这里可以看成给一个面值为m的钱币，要求将它换成n种不同的面值都为1的钱币，同时要求每种钱币供应的上下限。然后就是生成函数模板了。。。

My Code:

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

using namespace std;

const int N = 110;

int c1[N], c2[N];
int MIN[N], MAX[N];

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

    int n, m, i, j, k;
    while(~scanf("%d%d", &n, &m)) {
        memset(c1, 0, sizeof(c1));
        memset(c2, 0, sizeof(c2));

        for(i = 1; i <= n; ++i) {
            scanf("%d%d", &MIN[i], &MAX[i]);
        }
        c1[0] = 1;
        for(i = 1; i <= n; ++i) {
            for(j = 0; j <= m; ++j) {
                for(k = MIN[i]; k + j <= m && k <= MAX[i]; ++k) {
                    c2[k + j] += c1[j];
                }
            }
            for(j = 0; j <= m; ++j) {
                c1[j] = c2[j]; c2[j] = 0;
            }
        }
        cout << c1[m] << endl;
    }
    return 0;
}