mortennobel/cpp-cheatsheet
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Morten Nobel-Joergensen 2018-07-31 12:05:21 +02:00
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commit 06a4584ca2
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@ -447,7 +447,7 @@ a.first; // "hello"
a.second; // 3 a.second; // 3
``` ```
## `map` (associative array - usually implemented as binary search trees) ## `map` (associative array - usually implemented as binary search trees - avg. time complexity: O(log n))
```cpp ```cpp
#include <map> // Include map (std namespace) #include <map> // Include map (std namespace)
@ -458,7 +458,7 @@ for (auto& p:a)
a.size(); // 1 a.size(); // 1
``` ```
## `unordered_map` (associative array - usually implemented as hash table) ## `unordered_map` (associative array - usually implemented as hash table - avg. time complexity: O(1))
```cpp ```cpp
#include <unordered_map> // Include map (std namespace) #include <unordered_map> // Include map (std namespace)
@ -469,7 +469,7 @@ for (auto& p:a)
a.size(); // 1 a.size(); // 1
``` ```
## `set` (store unique elements - usually implemented as binary search trees) ## `set` (store unique elements - usually implemented as binary search trees - avg. time complexity: O(log n))
```cpp ```cpp
#include <set> // Include set (std namespace) #include <set> // Include set (std namespace)
@ -480,7 +480,7 @@ if (s.find(123) != s.end()) // Search for an element
cout << s.size(); // Number of elements in set cout << s.size(); // Number of elements in set
``` ```
## `unordered_set` (store unique elements - usually implemented as a hash set) ## `unordered_set` (store unique elements - usually implemented as a hash set - avg. time complexity: O(1))
```cpp ```cpp
#include <unordered_set> // Include set (std namespace) #include <unordered_set> // Include set (std namespace)
@ -501,3 +501,18 @@ sort(a, a+n); // Sort array a[0]..a[n-1] by <
sort(a.begin(), a.end()); // Sort vector or deque sort(a.begin(), a.end()); // Sort vector or deque
reverse(a.begin(), a.end()); // Reverse vector or deque reverse(a.begin(), a.end()); // Reverse vector or deque
``` ```
## 'chrono' (Time related library)
```cpp
#include <chrono> // Include chrono
using namespace chrono; // Use namespace
auto from = // Get current time_point
high_resolution_clock::now();
// ... do some work
auto to = // Get current time_point
high_resolution_clock::now();
using ms = // Compute duration in milliseconds
duration<float, milliseconds::period>;
cout << duration_cast<ms>(to - from)
.count() << "ms";
```