代码随想录day32

qq_535544962024-06-24 18:16

一旦有重叠区域，则用min更新右边界

python 复制代码

class Solution(object):
    def findMinArrowShots(self, points):
        """
        :type points: List[List[int]]
        :rtype: int
        """
        points.sort(key=lambda x:x[0])
        if len(points)==0:
            return 0

        count = 1
        
        for i in range(1, len(points)):
            if points[i][0] > points[i-1][1]:
                count += 1
            else:
                points[i][1] = min(points[i-1][1],points[i][1])
                
        return count

跟上题一模一样

python 复制代码

class Solution(object):
    def eraseOverlapIntervals(self, intervals):
        """
        :type intervals: List[List[int]]
        :rtype: int
        """
        intervals.sort(key=lambda x:x[0])
        if len(intervals)==0:
            return 0

        count = 0
        
        for i in range(1, len(intervals)):
            if intervals[i][0] < intervals[i-1][1]:
                count += 1
                intervals[i][1] = min(intervals[i-1][1],intervals[i][1])

                
        return count

第三题

构建哈希表，记录每个字母最大位置缩影，重新遍历，不断更新最大位置索引

python 复制代码

class Solution(object):
    def partitionLabels(self, s):
        """
        :type s: str
        :rtype: List[int]
        """
        hashmap = {}
        result = [] 
        for i in range(len(s)):
            hashmap[s[i]] = i

        left,right = 0, 0
        
        for i in range(len(s)):
            right = max(hashmap[s[i]],right) #不断更新最大位置索引，直到i==最大位置索引
            if right == i:
                result.append(right-left+1)#返回长度
                left = i + 1
        return result