Hdu--1331--function Run fun--Memory Search

Function Run FunTime limit:2000/1000 MS (java/others) Memory limit:65536/32768 K (java/others) Total Submission (s): 2376 Accepted Submission (s): 1187

Problem descriptionwe 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 > B > or C >, 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 a easy function to implement. The problem is, if implemented directly, for moderate values of a, B and C (for example, a = d, B = d, c = All), the prog Ram takes hours to run because of the massive recursion.

Inputthe input for your program would be a series of an integer triples, one per line, until the END-OF-FILE flag of-1-1-1. Using The above technique, you is to calculate W (A, B, c) efficiently and print the result.

Outputprint the value for W (a,b,c) for each triple.
Sample Input

Sample Output

W (1, 1, 1) = 2w (2, 2, 2) = 4w (Ten, 4, 6) = 523w (-1, 7, 18) = 1

Test instructions: Modify this recursion to you so that he can handle larger data

Parsing, A,b,c is controlled between 1~20, so memory of those data in a memory-search way prevents duplication.

#include <iostream> #include <cstdio> #include <cstring>using namespaceStd;intDp[ A][ A][ A],S=0; /  /Records prevent duplicate searchesintW(intA,intB,intC){if(A<=0||B<=0||C<=0)return1;if(A> -||B> -||C> -)returnW( -, -, -);if(Dp[A][B][C])returnDp[A][B][C]; /  /Use memory points to prevent duplicationif(A<B&&B<C)returnDp[A][B][C]=W(A,B,C-1)+W(A,B-1,C-1)-W(A,B-1,C);returnDp[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);}intMain (void){intA,B,C; while(~scanf("%d%d%d",&A,&B,&C))    {if(A==-1&&B==-1&&C==-1) Break;Memset(Dp,0,sizeof(Dp));Printf("W (%d,%d,%d) =%d\n",A,B,C,W(A,B,C)); }return0;}

Inexplicably, directly to the memory of the idea of adding in, it was really white alive AH!!

Hdu--1331--function Run fun--Memory Search