Leetcode LRU Cache solution for array [but Time Limit Exceeded]

lc_lru_cache_array.cpp

#include <vector>

struct LRUKV {
    int key_;
    int value_;
    LRUKV(int key, int value) :key_(key), value_(value) {}
};

class LRUCache {
public:
    LRUCache(int capacity) 
        :caches_(std::vector<LRUKV>(capacity, LRUKV(-1, -1))){
        
    }
    
    int get(int key) {
         // find
        for (std::vector<LRUKV>::size_type start = 0, end = caches_.size(); start < end; start++) 
        {
            if (caches_[start].key_ == key) {
                int value = caches_[start].value_;
                MoveToLast(start);
                return value;
            }
        }

        return -1;
    }
    
    void put(int key, int value) {
        // if exists key, only update
        for (std::vector<LRUKV>::size_type start = 0, end = caches_.size(); start < end; start++)
        {
            if (caches_[start].key_ == key) {
                caches_[start].value_ = value;
                // it have access
                MoveToLast(start);
                return;
            }
        }
        
        // if key is not exist, placement it to caches.
        // for (std::vector<LRUKV>::size_type start = 0, end = caches_.size(); start < end; start++)
        // {
        //     if (caches_[start].key_ == -1) {
        //         caches_[start].key_ = key;
        //         caches_[start].value_ = value;
        //         return;
        //     }
        // }

        // if key is not exist, placement it to caches first.
        for (std::vector<LRUKV>::size_type start = 0, end = caches_.size() - 1; start < end; start++)
        {
            caches_[start] = caches_[start + 1];
        }

        caches_[caches_.size() - 1] = LRUKV(key, value);
    }
    
  
private:
    void MoveToLast(size_t index)
    {
        LRUKV cache_temp = caches_[index];
        for (size_t start = index, end = caches_.size() - 1; start < end; start++)
        {
            caches_[start] = caches_[start + 1];
        }
        caches_[caches_.size() - 1] = cache_temp;
    }
    std::vector<LRUKV> caches_;
};

/**
 * Your LRUCache object will be instantiated and called as such:
 * LRUCache* obj = new LRUCache(capacity);
 * int param_1 = obj->get(key);
 * obj->put(key,value);
 */