Create h-index.cpp

C++/h-index.cpp

@@ -0,0 +1,18 @@
+// Time:  O(nlogn)
+// Space: O(1)
+
+class Solution {
+public:
+    int hIndex(vector<int>& citations) {
+        sort(citations.begin(), citations.end(), greater<int>());
+        int h = 0;
+        for (int i = 0; i < citations.size(); ++i) {
+            if (citations[i] >= i + 1) {
+                ++h;
+            } else {
+                break;
+            }
+        }
+        return h;
+    }
+};