Quick fact
std::find doesn't take customized comparator - std::find_if or std::find_if_not does.- not that when you find, you specify
InputIt first, InputIt last ...
- the search range is
[first, last) - not including the last
- when not found, it returns
last
- e.g. when you specify last not being the arr.end, and when the result is not found, the return val is the last, not the arr.end
- check code
find_if predicate example
- input type is the element type of the container.
class NaiveHashMap {
static constexpr int bucketCnt_ = 23;
using KeyVal = std::pair<int, int>;
using Bucket = std::list<KeyVal>;
std::vector<Bucket> buckets_;
int hash(int key) { return key % bucketCnt_; }
public:
MyHashMap() {
buckets_.resize(bucketCnt_);
}
int get(int key) {
auto& bucket = buckets_[hash(key)];
auto it = std::find_if(bucket.begin(), bucket.end(),
[&](const auto& p) { return p.first == key; });
if (it == bucket.end() || it->first != key)
return -1;
else
return it->second;
}
};