Score dice pairs
A dice game awards points from matching pairs. For each face value that appears more than once, every pair of matching dice contributes the face value to the total score.
- Count how many times each face value appears.
- A face appearing k times forms k*(k-1)/2 pairs.
- Each pair scores the face value.
- If no value repeats, the score is zero.
dicePairsScore(dice: list<int>) → int
C++ needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
int dicePairsScore(std::vector<int> dice) {
}Worked examples
| Call | Result |
|---|---|
dicePairsScore(std::vector<int>{2, 3, 2, 5, 3}) | 5 |
dicePairsScore(std::vector<int>{6, 6, 6}) | 18 |
dicePairsScore(std::vector<int>{1, 2, 3}) | 0 |
dicePairsScore(std::vector<int>{4, 4, 4, 4}) | 24 |
Hint
Count frequencies, then for each face with two or more occurrences add value * count * (count - 1) / 2.
Reference solution in C++
int dicePairsScore(std::vector<int> dice) {
std::map<int, int> freq;
for (int d : dice) freq[d]++;
int sum = 0;
for (const auto& p : freq) {
if (p.second >= 2) sum += p.first * p.second * (p.second - 1) / 2;
}
return sum;
}