Find coordinates in a vector c++ - c++

Question

I'm creating a game in Qt in c++, and I store every coordinate of specific size into a vector like :
std::vector<std::unique_ptr<Tile>> all_tiles = createWorld(bgTile);
for(auto & tile : all_tiles) {
tiles.push_back(std::move(tile));
}
Each level also has some healthpacks which are stored in a vector aswell.
std::vector<std::unique_ptr<Enemy>> all_enemies = getEnemies(nrOfEnemies);
for(auto &healthPackUniquePtr : all_healthpacks) {
std::shared_ptr<Tile> healthPackPtr{std::move(healthPackUniquePtr)};
int x = healthPackPtr->getXPos();
int y = healthPackPtr->getYPos();
int newYpos=checkOverlapPos(healthPackPtr->getXPos(),healthPackPtr->getYPos());
newYpos = checkOverlapEnemy(healthPackPtr->getXPos(),newYpos);
auto healthPack = std::make_shared<HealthPack>(healthPackPtr->getXPos(), newYpos, healthPackPtr->getValue());
healthPacks.push_back(healthPack);
}
But know I'm searching for the fastest way to check if my player position is at an healthpack position. So I have to search on 2 values in a vector : x and y position. Anyone a suggestion how to do this?

Answer 1

Your 'real' question:
I have to search on 2 values in a vector : x and y position. Anyone a
suggestion how to do this?"
Is a classic XY question, so I'm ignoring it!
I'm searching for the fastest way to check if my player position is at
an healthpack position.
Now we're talking. The approach you are using now won't scale well as the number of items increase, and you'll need to do something similar for every pair of objects you are interested in. Not good.
Thankfully this problem has been solved (and improved upon) for decades, you need to use a spacial partitioning scheme such as BSP, BVH, quadtree/octree, etc. The beauty of the these schemes is that a single data structure can hold the entire world in it, making arbitrary item intersection queries trivial (and fast).

Answer 2

You can implement a callback system. Then a player moves a tile, fire a callback to that tile which the player is on. Tiles should know its state and could add health to a player or do nothing if there is nothing on that tile. Using this technique, you don`t need searching at all.

Answer 3

If all_leathpacks has less than ~50 elements I wouldn't bother to improve. Simple loop is going to be sufficiently fast.
Otherwise you can split the vector into sectors and check only for the elements in the same sector as your player (and maybe a few around if it's close to the edge).
If you need something that's better for the memory you and use a KD-tree to index the healtpacks and search for them fast (O(logN) time).