Create find-the-number-of-ways-to-place-people-i.py

Author: kamyu104

Python/find-the-number-of-ways-to-place-people-i.py

@@ -0,0 +1,37 @@
+# Time:  O(n^2)
+# Space: O(1)
+
+# sort, array
+class Solution(object):
+    def numberOfPairs(self, points):
+        """
+        :type points: List[List[int]]
+        :rtype: int
+        """
+        points.sort(key=lambda x: (x[0], -x[1]))
+        result = 0
+        for i in xrange(len(points)):
+            y = float("-inf")
+            for j in xrange(i+1, len(points)):
+                if points[i][1] < points[j][1]:
+                    continue
+                if points[j][1] > y:
+                    y = points[j][1]
+                    result += 1
+        return result
+
+
+# Time:  O(n^3)
+# Space: O(1)
+# sort, array
+class Solution2(object):
+    def numberOfPairs(self, points):
+        """
+        :type points: List[List[int]]
+        :rtype: int
+        """
+        points.sort(key=lambda x: (x[0], -x[1]))
+        return sum(all(not points[i][1] >= points[k][1] >= points[j][1] for k in xrange(i+1, j))
+                   for i in xrange(len(points))
+                   for j in xrange(i+1, len(points)) if points[i][1] >= points[j][1])
+