Update 1552. Magnetic Force Between Two Balls

1000+/1552. Magnetic Force Between Two Balls

@@ -30,3 +30,36 @@ class Solution {
         return count >= m;
     }
 }
+
+
+class Solution {
+    public int maxDistance(int[] position, int m) {
+        Arrays.sort(position);
+        int low = 0;
+        int high = position[position.length-1];
+        while (low < high) {
+            int mid = low + (high-low+1)/2;
+            if (canPut(position, m, mid)) {
+                low = mid;
+            } else {
+                high = mid-1;
+            }
+        }
+        return low;
+    }
+
+    /*
+    * returns whether we can put m balls such that minimum distance between two consecutive ball is always greater than or equal to the max.
+    */
+    private boolean canPut(int[] positions, int m, int max) {
+        int count = 1;
+        int last = positions[0];
+        for (int i = 0; i < positions.length; i++) {
+            if (positions[i] - last >= max) {
+                last = positions[i];
+                count++;
+            }
+        }
+        return count >= m;
+    }
+}