Can I use std::partial_sort to sort a std::map?

Question

有两个数组，一个用于ID，一个用于分数，我想将两个数组存储到std::map ，并使用std::partial_sort查找五个最高分数，然后打印其ID，因此，是否有可以在std::map上使用std::partial_sort吗？

Answer 1

No.

You can't rearrange the items in a std::map . It always appears to be sorted in ascending key order.

Answer 2

In std::map , sorting applies only to keys. You can do it using vector:

//For getting Highest first
bool comp(const pair<int, int> &a, const pair<int, int> &b){
    return a.second > b.second; 
}
int main() {
    typedef map<int, int> Map;
    Map m = {{21, 55}, {11, 44}, {33, 11}, {10, 5}, {12, 5}, {7, 8}};
    vector<pair<int, int>> v{m.begin(), m.end()};
    std::partial_sort(v.begin(), v.begin()+NumOfHighestScorers, v.end(), comp);
    //....
}

Here is the Demo