# Chip Factory---hdu5536 (xor value max, 01 dictionary tree)

Source: Internet
Author: User

Test instructions: There is an array of a[], containing n number, found from n number of three number to make (A[i]+a[j]) ⊕a[k] The largest, i,j,k different;

The result is the largest, so we can use 01 dictionary tree, first put all the numbers into the dictionary tree, from the n number of two a[i] and A[j],

First remove them from the dictionary tree, and then find and a[i]+a[j] different or maximum number, and the result to take the maximum value;

Finally, do not forget to add a[i] and a[j] to the dictionary tree;

`#include <stdio.h>#include<string.h>#include<algorithm>#include<iostream>#include<vector>#include<queue>#include<Set>using namespacestd;#defineMet (A, b) memset (A, B, sizeof (a))#defineN 1005#defineINF 0x3f3f3f3ftypedefLong LongLL;structnode{intnum, sum;///num is the current number, and sum indicates whether it exists;node* next;};voidAdd (node* Head,intXintCNT) {Node*p = head;///move the pointer;     for(intI= to; i>=0; i--)    {        intK = (x>>i) &1;///indicates that x corresponds to the binary number from the right number I-bit is K (0 or 1);        if(P->next[k] = = NULL)///Create a new node if it does not exist;{node* Q =Newnode (); P-&GT;NEXT[K] =Q; } P= p->next[k];///move the pointer toward the next node;P->sum + = cnt;///The current node can be reached; update, if the addition of X is +1, delete x 1;} P->num = x;///at the end of the record, the number represented by the head to the current position is x;}intFind (node* Head,intx) {Node*p =Head;  for(intI= to; i>=0; i--)    {        intK = (x>>i) &1; if(p->next[k^1]! = NULL && p->next[k^1]->sum >0)///every time we try to move in different directions, the premise is that there are different nodes;p = p->next[k^1]; ElseP= p->Next[k]; }    return(P-&GT;NUM^X);///the last found P->num is the number that is different from X or Max;}intMain () {intT; scanf ("%d", &T);  while(t--)    {        intN, A[n]; Node*head =Newnode (); scanf ("%d", &N);  for(intI=1; i<=n; i++) {scanf ("%d", &A[i]); Add (Head, A[i],1);///Add all the numbers to the dictionary tree;        }        intAns =0; ///select two numbers a[i] and a[j] from the n number to remove them from the dictionary tree First,///then find and A[i]+a[j] The number of different or maximum, and the maximum value can be obtained;///Finally, do not forget to add a[i] and a[j] to the dictionary tree;         for(intI=1; i<=n; i++) {Add (head, A[i],-1);  for(intj=1; j<=n; J + +)            {                if(I==J)Continue; Add (Head, A[j],-1); intret = Find (head, a[i]+A[j]); Ans=Max (ans, ret); Add (Head, A[j],1); } Add (Head, A[i],1); } printf ("%d\n", ans); }    return 0;}`
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Chip Factory---hdu5536 (xor value max, 01 dictionary tree)

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