CodeForces Round #173 (282E)-Sausage Maximization dictionary tree

#include<iostream>#include<string.h>#include<algorithm>#include<cmath>#include<queue>#include<stdio.h>#include<stack>#define oo 1000000007#define ll long long#define pi acos(-1.0)using namespace std;struct node{       int son[2];        ll w;}p[10000005];ll a[100005],totol,ans,_2jie[45];int num;void InsertToTrie(ll x){       int h=0,i,t;       for (i=40;i>=0;i--)       {             if (x & _2jie[i]) t=1;                else t=0;             if (!p[h].son[t]) p[h].son[t]=++num;             h=p[h].son[t];       }              p[h].w=x;       return;}ll SerchMax(ll x){       int h,i,t;       h=0;       for (i=40;i>=0;i--)       {             if (x & _2jie[i]) t=1;                else t=0;             if (p[h].son[1-t]) h=p[h].son[1-t];                else h=p[h].son[t];        }       return p[h].w;} int main(){       int i,n;       ll prefix,postfix;        _2jie[0]=1;       for (i=1;i<=40;i++) _2jie[i]=_2jie[i-1]*2;       while (~scanf("%d",&n))       {             postfix=0;             for (i=1;i<=n;i++) scanf("%I64d",&a[i]),postfix^=a[i];              memset(p,0,sizeof(p));             ans=postfix;             num=0;             prefix=0;             InsertToTrie(0);             for (i=1;i<=n;i++)             {                    prefix^=a[i];                    InsertToTrie(prefix);                    postfix^=a[i];                     ans=max(ans,SerchMax(postfix)^postfix);             }             printf("%I64d\n",ans);           }       return 0;}