最简单的解决方案是从右到左遍历输入，对于每个元素，查找树中第一个更大的元素（或具有O（LogN）查找和插入的任何数据结构），然后将该元素添加到树中。这样，更大的元素将始终位于输入中的元素之后。

The simplest solution is to iterate over the input from right to left, and for each element look up the first greater element in a tree (or any data structure with O(LogN) look-up and insertion), and then add the element to the tree. That way the greater element always comes after the element in the input.

对于C ++版本，可以使用 std :: map ，其中元素的值是键，而元素在输入中的索引为值，并使用 upper_bound 获取下一个更大的值：

For a C++ version, you can use a std::map where the element's value is the key and the element's index in the input is the value, and use upper_bound to get the next greater value:

#include <iostream>
#include <vector>
#include <map>

void nextValues(std::vector<int> &in, std::vector<int> &out) {
    std::map<int, int> tree;
    for (int i = in.size() - 1; i >= 0; i--) {
        out.insert(out.begin(), tree.upper_bound(in[i])->second - 1);
        tree.insert(std::pair<int, int>(in[i], i + 1));
    }
}

int main() {
    std::vector<int> a = {80,19,49,45,65,71,76,28,68,66};
    std::vector<int> b;
    nextValues(a, b);
    for (int i : b) std::cout << (int) i << ","; // -1,7,4,4,9,6,-1,9,-1,-1
    return 0;
}