120 lines
3.2 KiB
C++
120 lines
3.2 KiB
C++
#ifndef INTERVALMAP_H
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#define INTERVALMAP_H
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#include <iostream>
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#include <iterator> //std::prev
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#include <memory> //std::shared_ptr
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#include <map>
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template <typename V>
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class IntervalMap
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{
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public:
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~IntervalMap(){
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treemap.clear();
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}
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void insert(int start, int end, V value)
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{
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if (start >= end)
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return;
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// c++ has no builtin function to find the greater key LESS THAN the supplied key. The solution I've found is to get an iterator to the key with find() and traverse back with std::prev
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const auto &tmp = treemap.lower_bound(end);
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const auto &end_prev_entry = tmp != treemap.begin() && tmp != treemap.end() ? std::prev(tmp) : tmp; // first element before end
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const auto &end_next_entry = tmp; // first element after end
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V v{};
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if (end_next_entry == treemap.end())
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{
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if (end_prev_entry != treemap.end() && end_prev_entry->first > start)
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treemap[end] = (V)(end_prev_entry->second);
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else
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treemap[end] = v;
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}
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else
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{
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if(end_next_entry->first != end)
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treemap[end] = end_prev_entry->second;
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// A little optimization: delete next key if it is of the same value of the end key
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//if(end_next_entry->second == treemap[end]) treemap.erase(end_next_entry);
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}
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// insert the start key. Replaces whatever value is already there. Do not place if the element before is of the same value
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treemap[start] = value;
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treemap.erase(treemap.upper_bound(start), treemap.lower_bound(end));
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}
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void remove(int at)
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{
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treemap.erase(at);
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}
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V at(int index)
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{
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const auto tmp = treemap.lower_bound(index);
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const auto r = tmp != treemap.begin() && tmp->first!=index ? std::prev(tmp) : tmp;
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return r->second;
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}
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void print()
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{
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for (auto i = treemap.begin(); i != treemap.end(); i++)
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std::cout << i->first << ": " << (int)(i->second) << "\n";
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if(!treemap.empty()) std::cout << "end key: " << std::prev(treemap.end())->first << "\n";
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}
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std::unique_ptr<V[]> toArray(int *length)
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{
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if (treemap.empty())
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{
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*length = 0;
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return nullptr;
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}
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const auto &end = std::prev(treemap.end());
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*length = end->first;
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if(*length == 0) return nullptr;
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std::unique_ptr<V[]> arr(new V[*length]);
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auto start = treemap.begin();
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for (auto i = std::next(treemap.begin()); i != treemap.end(); i++)
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{
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for (int k = start->first; k < i->first; k++)
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arr[k] = start->second;
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start = i;
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}
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return arr;
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}
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void fromArray(V *arr, int length)
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{
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treemap.clear();
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if (length == 0)
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return;
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V prev = arr[0];
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unsigned int prev_start = 0;
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for (unsigned int i = 1; i < length; i++)
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{
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if (prev != arr[i])
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{
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insert(prev_start, i, prev);
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prev_start = i;
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}
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prev = arr[i];
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}
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insert(prev_start, length, prev);
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}
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private:
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std::map<int, V> treemap{};
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};
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#endif
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