Create rank-transform-of-an-array.cpp

Author: kamyu104

C++/rank-transform-of-an-array.cpp

@@ -0,0 +1,19 @@
+// Time:  O(nlogn)
+// Space: O(n)
+
+class Solution {
+public:
+    vector<int> arrayRankTransform(vector<int>& arr) {
+        set<int> lookup{arr.cbegin(), arr.cend()};
+        unordered_map<int, int> rank;
+        for (const auto& v : lookup) {
+            rank[v] = rank.size() + 1;
+        }
+        vector<int> result;
+        transform(arr.cbegin(), arr.cend(), back_inserter(result),
+                  [&rank](const auto& v) {
+                      return rank[v];
+                  });
+        return result;
+    }
+};