Range Addition

也是陈年老题了，关键在于没想到结束位置应该用负数，其实再仔细一想，这个技巧就是扫描线原理而已

class Solution(object):
    def getModifiedArray(self, length, updates):
        """
        :type length: int
        :type updates: List[List[int]]
        :rtype: List[int]
        """
        result = [0] * length
        for start, end, value in updates:
            result[start] += value
            if end + 1 < length:
                result[end + 1] -= value

        for i in xrange(1, length):
            result[i] += result[i - 1]
        return result