STL Tips : std::unique

STL

std::unique

---

#include <algorithm>

---

std::unique

• std::unique used to remove consecutive duplicate elements from a range.
• The duplicated elements are moved to the end, therefore deletion doesn’t happen.
• For removing, call `container.erase(iter, container_end)

---

Example 01: Remove only CONSECUTIVE duplicates are removed.

std::vector<int> v = {1, 1, 2, 2, 2, 3, 3, 4, 2, 2, 5, 5, 6, 7};

auto new_end = std::unique(v.begin(), v.end());
v.erase(new_end, v.end());

for (int i : v) 
{
    std::cout << i << ' ';
}
// Output: 1 2 3 4 2 5 6 7 

Try here.

---

Example 02: Remove all duplicates with std::unique

std::vector<int> v = {1, 1, 2, 2, 2, 3, 3, 4, 2, 2, 5, 5, 6, 7};
std::sort(v.begin(), v.end());
auto new_end = std::unique(v.begin(), v.end());
v.erase(new_end, v.end());

for (int i : v) 
    std::cout << i << ' ';
// Output: 1 2 3 4 5 6 7 

Try here.