Create contains-duplicate-ii.cpp

kamyu104 · kamyu104 · commit 4e271b221e3d · 2015-05-29T10:32:43.000+08:00
diff --git a/C++/contains-duplicate-ii.cpp b/C++/contains-duplicate-ii.cpp
@@ -0,0 +1,22 @@
+// Time:  O(n)
+// Space: O(n)
+
+class Solution {
+public:
+    bool containsNearbyDuplicate(vector<int>& nums, int k) {
+        unordered_map<int, int> hash;
+        for (int i = 0; i < nums.size(); ++i) {
+            if (hash.find(nums[i]) == hash.end()) {
+                hash[nums[i]] = i;
+            } else {
+                // It the value occurs before, check the difference.
+                if (i - hash[nums[i]] <= k) {
+                    return true;
+                }
+                // Update the index of the value.
+                hash[nums[i]] = i;
+            }
+        }
+        return false;
+    }
+};
