Create magnetic-force-between-two-balls.cpp

Author: kamyu104

C++/magnetic-force-between-two-balls.cpp

@@ -0,0 +1,31 @@
+// Time:  O(nlogn + nlogr), r is the range of positions
+// Space: O(1)
+
+class Solution {
+public:
+    int maxDistance(vector<int>& position, int m) {
+        sort(begin(position), end(position));
+        int left = 0, right = position.back() - position.front();
+        while (left <= right) {
+            const auto& mid = left + (right - left) / 2;
+            if (!check(position, m, mid)) {
+                right = mid - 1;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return right;
+    }
+
+private:
+    bool check(const vector<int>& position, int m, int x) {
+        int count = 1, prev = position[0];
+        for (int i = 1; i < position.size(); ++i) {
+            if (position[i] - prev >= x) {
+                ++count;
+                prev = position[i];
+            }
+        }
+        return count >= m;
+    }
+};