数的计数

http://oj.acm.zstu.edu.cn/JudgeOnline/problem.php?id=2547

AC的递归

#include<stdio.h>
#include<string.h>
int main(){
	int n,f[1010];
	while(scanf("%d",&n)!=EOF){
		memset(f,0,sizeof(f));
		for(int i=1;i<=n;i++){
			for(int j=1;j<=i/2;j++){
				f[i]+=f[j];
			}
			f[i]+=1;
		}
		printf("%d\n",f[n]);
	}
	return 0;
}

肯定超时的dfs

#include<stdio.h>
#include<string.h>
int cnt;
void dfs(int x){
	cnt++;
	if(x==1) return;
	int xx=x/2;
	for(int i=xx;i>=1;i--){
		dfs(i);
	}
}
int main(){
	int n;
	while(scanf("%d",&n)!=EOF){
		cnt=0;
		dfs(n);
		printf("%d\n",cnt);
	}
	return 0;
}