nefuoj 16 Function Run Fun-白红宇

nefuoj 16 Function Run Fun

阅读量：4205 次

发布时间：2019-05-26

本文共 1556 字，大约阅读时间需要 5 分钟。

Function Run Fun

Problem:16

Time Limit:1000ms

Memory Limit:65536K

Description

We all love recursion! Don't we? Consider a three-parameter recursive function w(a, b, c): if a <= 0 or b <= 0 or c <= 0, then w(a, b, c) returns: 1 if a > 20 or b > 20 or c > 20, then w(a, b, c) returns: w(20, 20, 20) if a < b and b < c, then w(a, b, c) returns: w(a, b, c-1) + w(a, b-1, c-1) - w(a, b-1, c) otherwise it returns: w(a-1, b, c) + w(a-1, b-1, c) + w(a-1, b, c-1) - w(a-1, b-1, c-1) This is an easy function to implement. The problem is, if implemented directly, for moderate values of a, b and c (for example, a = 15, b = 15, c = 15), the program takes hours to run because of the massive recursion.

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 12 2 210 4 650 50 50-1 7 18-1 -1 -1

Sample Output

w(1, 1, 1) = 2w(2, 2, 2) = 4w(10, 4, 6) = 523w(50, 50, 50) = 1048576w(-1, 7, 18) = 1

Hint

dp

Source

pku #include 
      
       #include 
       
        using namespace std;long long data[50][50][50];long long inf(int x,int y,int z){    if(x<=0||y<=0||z<=0) return 1;    if(x>20||y>20||z>20)  return inf(20,20,20);    if(x
        
         
          >x>>y>>z)    {        if(x==-1&&y==-1&&z==-1)        break;        memset(data,-1,sizeof(data));        cout<<"w("<
          
           <<", "<
           
            <<", "<
            
             <<")"<<" = "<
             
              <