problems(cpp): add “1351. Count Negative Numbers in a Sorted Matrix”

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

problems/cpp/count-negative-numbers-in-a-sorted-matrix.cpp

@@ -0,0 +1,30 @@
+#include <algorithm>
+#include <cassert>
+#include <vector>
+
+class Solution {
+public:
+    int countNegatives(const std::vector<std::vector<int>>& grid)
+    {
+        auto last = 0;
+
+        auto negatives = 0;
+        for (const auto& row : grid) {
+            auto first_positive = std::lower_bound(row.crbegin() + last, row.crend(), 0);
+            auto i = first_positive - row.crbegin();
+
+            negatives += i;
+            last = i;
+        }
+        return negatives;
+    }
+};
+
+int main()
+{
+    Solution s;
+
+    assert((s.countNegatives(std::vector { std::vector { 4, 3, 2, -1 }, std::vector { 3, 2, 1, -1 }, std::vector { 1, 1, -1, -2 }, std::vector { -1, -1, -2, -3 } }) == 8));
+    assert((s.countNegatives(std::vector { std::vector { 3, 2 }, std::vector { 1, 0 } }) == 0));
+    return 0;
+}