HDU 2152 (母函數)

/*

母函數題；只是限定了一些範圍，加上就可以了；

http://acm.hdu.edu.cn/showproblem.php?pid=2152

*/

#include <iostream>using namespace std;#define maxn 105int a[maxn],b[maxn],minum[maxn],maxnum[maxn];int main(){int n,m;while(cin>>n>>m){for(int i = 0; i < n; i++){cin>>minum[i]>>maxnum[i];}memset(a,0,sizeof(a));memset(b,0,sizeof(b));for(int i = minum[0]; i <= maxnum[0]; i++)a[i] = 1;for(int i = 1; i < n; i++){for(int j = 0; j <= m; j++){for(int k = minum[i]; k + j<=m && k <= maxnum[i];k++){b[j+k] += a[j];}}for(int j = 0; j <= m; j++){a[j] = b[j];b[j] = 0;}}cout<<a[m]<<endl;}}