We all love recursion! Don't we? Input The input for your program will be a series of integer triples, one per line, until the end-of-file flag of -1 -1 -1. Using the above technique, you are to calculate w(a, b, c) efficiently and print the result. Output Print the value for w(a,b,c) for each triple. Sample Input 1 1 1 2 2 2 10 4 6 50 50 50 -1 7 18 -1 -1 -1 Sample Output w(1, 1, 1) = 2 w(2, 2, 2) = 4 w(10, 4, 6) = 523 w(50, 50, 50) = 1048576 w(-1, 7, 18) = 1 |
给你一个函数让你实现,但是这其中有很多重复计算的部分,比如15 15 15,直接调用函数会超时。
所以在计算的时候,保存下已经计算过的值,节省掉这部分时间:
#include<iostream>
using namespace std;
typedef long long ll;
ll m[50][50][50];
ll w(ll a,ll b,ll c){
if(a<=0||b<=0||c<=0) return 1;
if(m[a][b][c]) return m[a][b][c];
else if(a>20||b>20||c>20){
return w(20,20,20);
}
else if(a<b&&b<c){
return m[a][b][c]=w(a,b,c-1)+w(a,b-1,c-1)-w(a,b-1,c);
}
else return m[a][b][c]=w(a-1,b,c)+w(a-1,b-1,c)+w(a-1,b,c-1)-w(a-1,b-1,c-1);
}
int main(){
ll a,b,c;
while(cin>>a>>b>>c){
if(a==-1&&b==-1&&c==-1) break;
cout<<"w("<<a<<", "<<b<<", "<<c<<") = "<<w(a,b,c)<<endl;
}
return 0;
}