子数组的最大异或和

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子数组的最大异或和_牛客题霸_牛客网

算法：最大子数组异或和_异或值最大的子数组-优快云博客

#include <iostream>
#include <limits>
#include <new>
#include <vector>
using namespace std;

struct Trie {
    std::vector<Trie*> next;
    int val;
    Trie() {
        val = -1;
        next.resize(2, nullptr);
    }
};

void insert(Trie* root, int num) {
    if (!root) {
        return;
    }
    for (int i = 31; i >= 0; --i) {
        int index = (num >> i) & 1;
        if (!root->next[index]) {
            root->next[index] = new (std::nothrow) Trie;
        }
        root = root->next[index];
    }
    root->val = num;
}


int search(Trie* root, int num) {
    if (!root) {
        return -1;
    }
    for (int i = 31; i >= 0; --i) {
        int index = (num >> i) & 1;
        int target = 1 - index;
        if (i == 31) {
            target = index;
        }
        if (root->next[target]) {
            root = root->next[target];
        } else {
            root = root->next[1 - target];
        }
    }
    return root->val;
}

class Solution {
public:
    Solution() {

    }
    int solve(std::vector<int>& nums) {
        Trie* root = new (std::nothrow) Trie;
        int result = -1;
        int prefix_sum = 0;
        insert(root, 0);
        for (auto num : nums) {
            prefix_sum ^= num;
            insert(root, prefix_sum);
            int tmp = search(root, prefix_sum);
            result = max(result, tmp ^ prefix_sum);
        }
        return result;
    }
};

int main() {
    int a, b;    
    while (cin >> a) { // 注意 while 处理多个 case
        std::vector<int> nums;
        nums.reserve(a);
        for (int i = 0; i < a; ++i) {
            cin >> b;
            //cout << "b :" << b << endl;
            nums.push_back(b);
        }
        Solution sol;
        cout << sol.solve(nums) << endl;
    }
}
// 64 位输出请用 printf("%lld")