Consecutive Sum LightOJ - 1269(区间异或和)

Consecutive Sum

又来水一发blog...

本来是昨天补codechef的题，最后一道题是可持久化字典树，然后去黄学长博客看了看

觉得字典树写法有点不太一样，就想着用黄学长的板子写码几道题吧...

最后发现...其实是可持久化字典树跟普通字典树写法不一样...我好傻逼...

区间异或和

可以先把前缀异或和插入到字典树中，然后去贪心

求最大值就是要求从高到低尽量不一样

高位不一样优先

用一个bit数组来存放好看多了

偷偷摸摸顺便学了快读板子...虽说可能没啥用...

#include <bits/stdc++.h>
using namespace std;

const int maxn = 2e6 + ;

int sum[ + ];
int ans1, ans2;
int bit[];
inline int read() {
    int x = , f = ; char ch = getchar();
    while (ch < '' || ch > '') { if (ch == '-') f = -; ch = getchar(); }
    while (ch >= '' && ch <= '') { x = x *  + ch - ''; ch = getchar(); }
    return x * f;
}

struct Trie {
    int tol;
    int Next[maxn][];
    void init() {
        tol = ;
        memset(Next, , sizeof(Next));
    }
    void insert(int x) {
        int root = ;
        for (int i = ; i >= ; i--) {
            int id = x & bit[i]; id >>= i;
            if (!Next[root][id]) Next[root][id] = ++tol;
            root = Next[root][id];
        }
    }
    void query(int x) {
        int temp1 = , root1 = , root2 = , temp2 = ;
        for (int i = ; i >= ; i--) {
            int id = x & bit[i]; id >>= i;
            if (Next[root1][id ^ ]) root1 = Next[root1][id ^ ], temp1 += bit[i];
            else root1 = Next[root1][id];
            if (Next[root2][id]) root2 = Next[root2][id];
            else root2 = Next[root2][id ^ ], temp2 += bit[i];
        }
        ans1 = max(ans1, temp1);
        ans2 = min(ans2, temp2);
    }
} trie;

int main() {
    bit[] = ; for(int i = ; i <= ; i++) bit[i] = bit[i-] << ;
    int T;
    T = read();
   // cin >> T;
    int kase = ;
    while (T--) {
        int n = read();
      //  Trie trie;
        trie.init();
        ans1 = ;
        ans2 = 0x3f3f3f3f;
        trie.insert();
        for (int i = ; i <= n; i++) {
            int x; cin >> x;
            sum[i] = sum[i-] ^ x;
            trie.query(sum[i]);
            trie.insert(sum[i]);
        }
        printf("Case %d: %d %d", ++kase, ans1, ans2);
        puts("");
    }
    return ;
}