hdu 5524 二叉树找规律，二进制相关
input
n 1<=n<=1e18
output
有n个结点的满二叉树有多少个不相同结点数的子树
做法：树有h=log2(n)层，最多有2h-2种(1除外),然后再n减去u重复的即可
1 #include <bits/stdc++.h> 2 #include <cstdio> 3 #include <queue> 4 #include <cstring> 5 #include <iostream> 6 #include <cstdlib> 7 #include <algorithm> 8 #include <vector> 9 #include <map> 10 #include <set> 11 #include <ctime> 12 #include <cmath> 13 #include <cctype> 14 #include <string> 15 #include <bitset> 16 #define MAX 100000 17 #define LL long long 18 using namespace std; 19 LL n; 20 int highbit(LL x) 21 { 22 for(int i=63;i>=0;i--) if(x&(1LL<<i)) return i+1; 23 } 24 int lowbit(LL x) 25 { 26 for(int i=0;i<=63;i++) if(x&(1LL<<i)) return i; 27 } 28 int main() 29 { 30 freopen("in","r",stdin); 31 //scanf("%d",&T); 32 while(scanf("%lld",&n)==1) 33 { 34 int h=highbit(n); 35 LL maxn=(1LL<<h)-1;LL mid=maxn-(1LL<<(h-2>=0?h-2:0)); 36 // printf("%lld:",n); 37 // printf("h=%d maxn=%lld mid=%lld\n",h,maxn,mid); 38 if(n==maxn||n==mid) { printf("%d\n",h);continue; } 39 h+=h-2; 40 if(n<=mid) h--; 41 h-=lowbit(n-(maxn>>1)); 42 printf("%d\n",h); 43 } 44 //printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC); 45 return 0; 46 }
