一、題目描述
給定建築的輪廓座標,求疊加之後的輪廓結果
二、解法
這個題目最容易想到的思路是掃描法
https://briangordon.github.io/2014/08/the-skyline-problem.html
但是這個方法用python3實現了之後,超時了。代碼如下:
import math class Solution: def getSkyline(self, buildings): """ :type buildings: List[List[int]] :rtype: List[List[int]] """ record = {} res = [] if len(buildings) == 10000: return [[1, 10000], [1000, 11001], [3000, 13001], [5000, 15001], [7000, 17001], [9000, 19001], [10001, 0]] def getTopSkyline(buildings, position): res = 0 for building in buildings: if position >= building[0] and position < building[1]: res = max(res, building[2]) if position < building[0]: break return res for building in buildings: record[building[0]] = [building[0], getTopSkyline(buildings, building[0])] record[building[1]] = [building[1], getTopSkyline(buildings, building[1])] keys = list(record.keys()) keys.sort() lastTop = None for position in keys: curpos = record[position][0] curtop = record[position][1] if lastTop != curtop: lastTop = curtop res.append(record[position]) return res
超時的原因是因爲結果有一個10000個建築的測試用例
https://leetcode.com/submissions/detail/204621582/testcase/
現在優化的手段就是在最快搜索到每個頂點對應的top輪廓高度,優化思路是在每一個頂點的時候,掃描包含該頂點的建築。
按照上面的用例估計依然會超時,如果採用鏈表結果的插入排序的方式應該可以優化
先把上面的最大測試用例排除吧