36天【代码随想录算法训练营34期】第八章 贪心算法 part05( ● 435. 无重叠区间 ● 763.划分字母区间 ● 56. 合并区间 )

435. 无重叠区间

class Solution:
    def eraseOverlapIntervals(self, intervals: List[List[int]]) -> int:
        count = 0
        intervals.sort(key=lambda x: x[0])

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

763.划分字母区间

class Solution:
    def partitionLabels(self, s: str) -> List[int]:
        table = {}
        start = 0
        end = 0
        result = []

        for i in range(len(s)):
            table[s[i]] = i

        for i in range(len(s)):
            end = max(end, table[s[i]])
            if i == end:
                result.append(end-start+1)
                start = i+1
        return result

56. 合并区间

class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        if len(intervals) == 0:
            return intervals
        intervals.sort(key=lambda x: x[0])
        result = [intervals[0]]

        for i in range(1, len(intervals)):
            if result[-1][1] >= intervals[i][0]:
                result[-1][1] = max(intervals[i][1], result[-1][1])
            else:
                result.append(intervals[i])

        return result