链接：. - 力扣（LeetCode）

题解：把字母看成1，把数字看为-1，将题目变为求的和为0的最长连续子数组

class Solution {
public:
    vector<string> findLongestSubarray(vector<string>& array) {
        if (array.size() <= 0) {
            return {};
        }
        std::unordered_map<int, int> table;
        table[0] = -1;
        int sum = 0;
        int len = 0;
        int index = 0;
        for (int i = 0; i < array.size(); ++i) {
            const auto& num = array[i];
            if (isalpha(num[0])) {
                sum += 1;
            } else {
                sum -= 1;
            }
            auto it = table.find(sum);
            if (it != table.end()) {
                if (i - it->second > len) {
                    len = i - it->second;
                    index = it->second+1;
                }
            } else {
                table[sum] = i;
            }
        }
        std:vector<string> result;
        result.reserve(len);
        for (int i = 0; i < len; ++i) {
            result.push_back(array[index+i]);
        }
        return result;
    }
};