代码随想录算法训练营第三十六日| LC435. 无重叠区间 LC763.划分字母区间 LC56. 合并区间-优快云博客

这篇博客主要探讨了LeetCode中的三道算法题目，包括如何解决435.无重叠区间问题，探讨763.划分字母区间的策略，以及详细解析56.合并区间的算法实现。通过这些题目，作者旨在帮助读者提升解决区间操作的算法能力。

LC435. 无重叠区间：

class Solution:
    def eraseOverlapIntervals(self, intervals: List[List[int]]) -> int:
        if len(intervals) == 0: return 0
        intervals.sort(key=lambda x: x[1])
        count = 1 # 记录非交叉区间的个数
        end = intervals[0][1] # 记录区间分割点
        for i in range(1, len(intervals)):
            if end <= intervals[i][0]:
                count += 1
                end = intervals[i][1]
        return len(intervals) - count

LC763.划分字母区间

class Solution:
    def partitionLabels(self, s: str) -> List[int]:
        hash = [0] * 26
        for i in range(len(s)):
            hash[ord(s[i]) - ord('a')] = i
        result = []
        left = 0
        right = 0
        for i in range(len(s)):
            right = max(right, hash[ord(s[i]) - ord('a')])
            if i == right:
                result.append(right - left + 1)
                left = i + 1
        return result

LC56. 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 = []
        result.append(intervals[0])
        for i in range(1, len(intervals)):
            last = result[-1]
            if last[1] >= intervals[i][0]:
                result[-1] = [last[0], max(last[1], intervals[i][1])]
            else:
                result.append(intervals[i])
        return result