Create find-right-interval.py

Author: kamyu104

Python/find-right-interval.py

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+# Time:  O(nlogn)
+# Space: O(n)
+
+# Given a set of intervals, for each of the interval i,
+# check if there exists an interval j whose start point is bigger than or
+# equal to the end point of the interval i, which can be called that j is on the "right" of i.
+#
+# For any interval i, you need to store the minimum interval j's index,
+# which means that the interval j has the minimum start point to
+# build the "right" relationship for interval i. If the interval j doesn't exist,
+# store -1 for the interval i. Finally, you need output the stored value of each interval as an array.
+#
+# Note:
+# You may assume the interval's end point is always bigger than its start point.
+# You may assume none of these intervals have the same start point.
+# Example 1:
+# Input: [ [1,2] ]
+#
+# Output: [-1]
+#
+# Explanation: There is only one interval in the collection, so it outputs -1.
+# Example 2:
+# Input: [ [3,4], [2,3], [1,2] ]
+#
+# Output: [-1, 0, 1]
+#
+# Explanation: There is no satisfied "right" interval for [3,4].
+# For [2,3], the interval [3,4] has minimum-"right" start point;
+# For [1,2], the interval [2,3] has minimum-"right" start point.
+# Example 3:
+# Input: [ [1,4], [2,3], [3,4] ]
+#
+# Output: [-1, 2, -1]
+#
+# Explanation: There is no satisfied "right" interval for [1,4] and [3,4].
+# For [2,3], the interval [3,4] has minimum-"right" start point.
+#
+# Definition for an interval.
+# class Interval(object):
+#     def __init__(self, s=0, e=0):
+#         self.start = s
+#         self.end = e
+
+class Solution(object):
+    def findRightInterval(self, intervals):
+        """
+        :type intervals: List[Interval]
+        :rtype: List[int]
+        """
+        sorted_intervals = sorted((interval.start, i) for i, interval in enumerate(intervals))
+        result = []
+        for interval in intervals:
+            idx = bisect.bisect_left(sorted_intervals, (interval.end,))
+            result.append(sorted_intervals[idx][1] if idx < len(sorted_intervals) else -1)
+        return result