Two New Problems "Contains Duplicate II/III"

Author: haoel

README.md

@@ -7,6 +7,8 @@ LeetCode
 
 | # | Title | Solution | Difficulty |
 |---| ----- | -------- | ---------- |
+|204|[Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii/)| [C++](./algorithms/containsDuplicate/ContainsDuplicate.III.cpp)|Medium|
+|203|[Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)| [C++](./algorithms/containsDuplicate/ContainsDuplicate.II.cpp)|Easy|
 |202|[The Skyline Problem](https://leetcode.com/problems/the-skyline-problem/)| [C++](./algorithms/theSkylineProblem/TheSkylineProblem.cpp)|Hard|
 |201|[Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)| [C++](./algorithms/containsDuplicate/ContainsDuplicate.cpp)|Easy|
 |200|[Combination Sum III](https://leetcode.com/problems/combination-sum-iii/)| [C++](./algorithms/combinationSum/combinationSum.III.cpp)|Medium|

algorithms/containsDuplicate/ContainsDuplicate.II.cpp

@@ -0,0 +1,28 @@
+// Source : https://leetcode.com/problems/contains-duplicate-ii/
+// Author : Hao Chen
+// Date   : 2015-06-12
+
+/********************************************************************************** 
+ * 
+ * Given an array of integers and an integer k, find out whether there there are 
+ * two distinct indices i and j in the array such that nums[i] = nums[j] and 
+ * the difference between i and j is at most k.
+ * 
+ *               
+ **********************************************************************************/
+
+class Solution {
+public:
+    bool containsNearbyDuplicate(vector<int>& nums, int k) {
+        unordered_map<int, int> m;
+        for (int i=0; i<nums.size(); i++) {
+            int n = nums[i];
+            if (m.find(n) != m.end() && i - m[n] <= k) {
+                return true;
+            }
+            m[n] = i;
+        }
+        return false;
+    }
+};
+

algorithms/containsDuplicate/ContainsDuplicate.III.cpp

@@ -0,0 +1,40 @@
+// Source : https://leetcode.com/problems/contains-duplicate-iii/
+// Author : Hao Chen
+// Date   : 2015-06-12
+
+/********************************************************************************** 
+ * 
+ * Given an array of integers, find out whether there are two distinct indices i and j 
+ * in the array such that the difference between nums[i] and nums[j] is at most t and 
+ * the difference between i and j is at most k.
+ *               
+ **********************************************************************************/
+
+
+
+class Solution {
+public:
+    bool containsNearbyAlmostDuplicate(vector<int>& nums, int k, int t) {
+        if(nums.size() < 2 || k == 0) return false;
+        int low = 0;
+        //maintain a sliding window 
+        set<long long> window;
+        for (int i=0; i<nums.size(); i++){
+            //make sure window size <= k
+            if (i - low > k) {
+                window.erase(nums[low]);
+                low++;
+            }
+            
+            // lower_bound() is the key, 
+            // it returns an iterator pointing to the first element >= val 
+            auto it = window.lower_bound((long long)nums[i] - (long long)t );
+            if (it != window.end() && abs((long long)nums[i] - *it) <= (long long)t) {
+                return true;
+            }
+            window.insert(nums[i]);
+        }
+        return false;
+    }
+};
+