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Author: assassint2017

K Closest Points to Origin/K_Closest_Points_to_Origin.cpp

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+// 依然是使用堆排序的思想
+// Runtime: 240 ms, faster than 68.34% of C++ online submissions for K Closest Points to Origin.
+// Memory Usage: 45 MB, less than 60.94% of C++ online submissions for K Closest Points to Origin.
+
+struct cell
+{
+    cell (int x, int y, double d) : x(x), y(y), dis(d) {}
+
+    int x, y;
+    double dis;
+};
+
+class Solution 
+{
+public:
+    vector<vector<int>> kClosest(vector<vector<int>>& points, int k) 
+    {
+        vector<vector<int>> res;
+
+        vector<cell> heap;
+        for (int i = 0; i < k; ++i)
+        {
+            heap.push_back(cell(points[i][0], points[i][1], getdis(points[i][0], points[i][1])));
+        }
+
+        make_heap(heap.begin(), heap.end(), key);
+
+        for (int i = k; i < points.size(); ++i)
+        {
+            if (heap[0].dis > getdis(points[i][0], points[i][1]))
+            {
+                pop_heap(heap.begin(), heap.end(), key);
+                heap.pop_back();
+
+                heap.push_back(cell(points[i][0], points[i][1], getdis(points[i][0], points[i][1])));
+                push_heap(heap.begin(), heap.end(), key);
+            }
+        }
+
+        for (auto item : heap)
+        {
+            vector<int> temp(2, 0);
+            temp[0] = item.x;
+            temp[1] = item.y;
+            res.push_back(temp);
+        }
+
+        return res;
+    }
+private:
+    bool(*key)(const cell&, const cell&) = [](const cell& pos1, const cell& pos2){return pos1.dis < pos2.dis; };
+private:
+    double getdis(int x, int y)
+    {
+        return (x * x) + (y * y);
+    }
+};