Add bubble sort

sort/bubble_sort.cpp

@@ -0,0 +1,25 @@
+#include <vector>
+#include "../utils/helpers.h"
+
+void bubble_sort(std::vector<int> &nums)
+{
+  for (size_t i = 0; i < nums.size(); i++)
+  {
+    for (size_t j = 1; j < nums.size() - i; j++)
+    {
+      if (nums[j] < nums[j - 1])
+      {
+        int temp = nums[j];
+        nums[j] = nums[j - 1];
+        nums[j - 1] = temp;
+      }
+    }
+  }
+}
+
+int main()
+{
+  std::vector<int> nums{6, 9, -3, 20, 55, 2, 11, 13};
+  bubble_sort(nums);
+  print_nums(nums);
+}