problems(cpp): add “1685. Sum of Absolute Differences in a Sorted Array”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/cpp/sum-of-absolute-differences-in-a-sorted-array.cpp

@@ -0,0 +1,36 @@
+#include <algorithm>
+#include <cassert>
+#include <numeric>
+#include <vector>
+
+class Solution {
+   public:
+    std::vector<int> getSumAbsoluteDifferences(const std::vector<int>& nums) {
+        auto total = std::accumulate(nums.begin(), nums.end(), 0);
+
+        auto left = 0;
+        std::vector<int> result;
+        for (auto i = 0u; i < nums.size(); ++i) {
+            auto left_diff = i * nums[i] - left;
+
+            auto right = total - nums[i] - left;
+            auto right_diff = right - (nums.size() - i - 1) * nums[i];
+
+            result.push_back(left_diff + right_diff);
+
+            left += nums[i];
+        }
+
+        return result;
+    }
+};
+
+int main() {
+    Solution s;
+
+    assert((s.getSumAbsoluteDifferences(std::vector{2, 3, 5}) ==
+            std::vector{4, 3, 5}));
+    assert((s.getSumAbsoluteDifferences(std::vector{1, 4, 6, 8, 10}) ==
+            std::vector{24, 15, 13, 15, 21}));
+    return 0;
+}