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96_bak.c
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96_bak.c
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/*************************************************************************
* File Name : 96_bak.c
* Author : unasm
* Mail : unasm@sina.cn
* Last_Modified: 2015-05-14 16:51:47
************************************************************************/
#include<stdio.h>
#define MAX 100000
int been[MAX];
int digui(n) {
if(n < MAX && been[n] != 0 ) {
return been[n] ;
}
if(n <= 1) {
been[n] = 1;
return been[n];
}
int ans = 0;
n--;
for(int i = 0;i <= n ;i++) {
ans += digui(i) * digui(n - i);
}
if((n+ 1) < MAX ){
been[n + 1] = ans;
}
return ans;
}
int min (int a,int b) {
return a > b ? b: a;
}
int numTrees(int n) {
for(int i = 0,end = min(n,MAX); i < end;i++) {
been[i] = 0;
}
return digui(n);
/*
printf("%d\n", digui(2));
printf("%d\n", digui(3));
printf("%d\n", digui(4));
return 0;
*/
}
int main(int argc, const char *argv[])
{
printf("%d\n", numTrees(5)) ;
return 0;
}