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  1. #include <list>
  2. #include <unordered_map>
  3.  
  4. class LRUCache {
  5. public:
  6.     const size_t capacity;
  7.     std::list<int> lru;
  8.     std::unordered_map<size_t, std::list<int>::iterator> cache;
  9.     std::unordered_map<size_t, size_t> key_val_map;
  10.  
  11.     LRUCache(const size_t capacity) : capacity(capacity) {}
  12.  
  13.     int get(size_t key) {
  14.         if (key_val_map.count(key) == 0) {
  15.             return -1;
  16.         }
  17.  
  18.         make_most_recent(key);
  19.         return key_val_map[key];
  20.     }
  21.  
  22.     void put(size_t key, size_t value) {
  23.         if (key_val_map.size() == capacity && key_val_map.count(key) == 0) {
  24.             pop();
  25.         }
  26.  
  27.         make_most_recent(key);
  28.  
  29.         key_val_map[key] = value;
  30.     }
  31.  
  32. private:
  33.     void make_most_recent(size_t key) {
  34.         if (key_val_map.count(key)) {
  35.             lru.erase(cache[key]);
  36.         }
  37.  
  38.         lru.push_front(key);
  39.         cache[key] = lru.begin();
  40.     }
  41.  
  42.  
  43.     void pop() {
  44.         key_val_map.erase(lru.back());
  45.         cache.erase(lru.back());
  46.         lru.pop_back();
  47.     }
  48. };
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
stdout
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Standard output is empty
https://ideone.com/ZZJud5
language:
C++ (gcc 8.3)
created:
3 years ago
visibility:
public

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