436. Find Right Interval ——本质：查找题目，因此二分！

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:

1. You may assume the interval's end point is always bigger than its start point.
2. 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]
Input: [ [3,4], [2,3], [1,2] ]
Output: [-1, 0, 1]
[1, 2], [2, 3], [3, 4]
2,      1,    0
1,      0,  -1
 
Input: [ [1,4], [2,3], [3,4] ]
Output: [-1, 2, -1]
[1, 4], [2, 3], [3, 4], [4, 5] sorted
        """
        from bisect import bisect_left
        starts = []
        pos_dict = {}
        for i,v in enumerate(intervals):
            pos_dict[v.start] = i
            starts.append(v.start)
        starts.sort()
        ans = [-1]*len(intervals)
        for i,v in enumerate(intervals):
            pos = bisect_left(starts, v.end)
            if pos>=0 and pos<len(intervals):
                ans[i] = pos_dict[starts[pos]]
        return ans