By now, the fastest comparison sorting algorithm is \(Ο(N\log N)\). The sort() function in STL implemented with an optimized quicksort, which is always \(O(N\log N)\).

Here is an example:

In Python, we have tuple, and in Java, we have Map, but in C++, the language itself doesn’t contain anything equivalent. Nevertheless, we can use STL - the Standard Template Library - to construct the data structure.

Of course, we can construct this by ourself, and it’s not complex, but as we will see, with “pair” we can make it easier and simpler.

This is an example:

To record the time your program costs, you can use the function clock(), that is defined in <ctime>. Here is an example showing how to use this function:

This is a Binary-Search Tree template written by Leon.

This problem can be solved by at least 4 methods:

• Quick Sort
• Binary Search Tree
• Trie and Depth First Search
• Map

Here is my pseudo code:

1
2
3
4
5
6
7

count <-- 0
for each edge( two points) do
    find the possible other two points to construct a square, there will be two pairs.
    for each pair of points do
        use binary search or hash to check if both points are given
        if both are given then count <-- count+1
return count

When VC6.0 breaks down due to a stack overflow, sometimes you can adjust the stack allocations to get around this problem.

Project->Settings->Link->Category->Output

Write the bytes you need in Stack allocations->Reserve.