Create Day30.cpp

Author: starwiz-7

Day30.cpp

@@ -0,0 +1,37 @@
+/*
+    Author: Aryan Yadav
+    K Closest Points to Origin
+    Difficulty: Medium
+*/
+
+class Solution {
+    private:
+    bool farther(vector<int>& p,vector<int>& q){
+        return p[0]*p[0]+p[1]*p[1]>q[0]*q[0]+q[1]*q[1];
+    }
+    bool closer(vector<int>& p,vector<int>& q){
+        return p[0]*p[0]+p[1]*p[1]<q[0]*q[0]+q[1]*q[1];
+    }
+    int partition(vector<vector<int>>& points,int left,int right){
+        int pivot=left,l=left+1,r=right;
+        while(l<=r){
+            if(farther(points[l],points[pivot]) && closer(points[r],points[pivot]))
+                swap(points[l++],points[r--]);
+            if(!farther(points[l],points[pivot])) l++;
+            if(!closer(points[r],points[pivot])) r--;
+        }
+        swap(points[pivot], points[r]);
+        return r;
+    }
+public:
+    vector<vector<int>> kClosest(vector<vector<int>>& points, int k) {
+        int l=0,r = points.size()-1;
+        while(true){
+            int p = partition(points,l,r);
+            if(p == k-1) break;
+            if(p<k-1) l = p+1;
+            else r = p-1;
+        }
+        return vector<vector<int>>(points.begin(), points.begin()+k);
+    }
+};