#839 · #2406 · Divide Intervals Into Minimum Number of Groups(将区间分为最少组数)

You are given a 2D array intervals. Divide the intervals into the minimum number of groups such that no two intervals in the same group overlap. Two intervals overlap if they share at least one point. Return the minimum number of groups. Constraints: 1 <= intervals.length <= 10^5, 1 <= left <= right <= 10^6.