2017/3/31

XingwenZhang · XingwenZhang · commit d2b7ae68a104 · 2017-03-31T22:52:34.000-07:00
diff --git a/No219_ContainsDuplicateII.cpp b/No219_ContainsDuplicateII.cpp
@@ -0,0 +1,42 @@
+// Given an array of integers and an integer k, find out whether there are 
+// two distinct indices i and j in the array such that nums[i] = nums[j] and 
+// the absolute difference between i and j is at most k.
+
+
+// class Solution {
+// public:
+// 	// This method will TLE
+//     bool containsNearbyDuplicate(vector<int>& nums, int k) {
+//         int n = nums.size();
+//         for(int i = 0; i<n; i++){
+//         	for(int j=i+1; j<=i+k && j < n; j++){
+//         		if(nums[i] == nums[j]){
+//         			return true;
+//         			break;
+//         		}
+//         	}
+//         }
+//         return false;
+//     }
+// };
+
+
+class Solution {
+public:
+	// Sliding windows
+    bool containsNearbyDuplicate(vector<int>& nums, int k) {
+        unordered_set<int> hashSet;
+        for(int i=0; i<nums.size(); i++){
+        	if(i > k){
+        		hashSet.erase(nums[i-k-1]);
+        	}
+
+        	// Take care! here not judge if i>k, it operates everytime
+        	if(!hashSet.insert(nums[i]).second){
+        		return true;
+        	}
+        }
+        return false;
+    }
+};
+
