# ---
# title: 757. Set Intersection Size At Least Two
# id: problem757
# author: Tian Jun
# date: 2020-10-31
# difficulty: Hard
# categories: Greedy
# link: <https://leetcode.com/problems/set-intersection-size-at-least-two/description/>
# hidden: true
# ---
# 
# An integer interval `[a, b]` (for integers `a < b`) is a set of all
# consecutive integers from `a` to `b`, including `a` and `b`.
# 
# Find the minimum size of a set S such that for every integer interval A in
# `intervals`, the intersection of S with A has a size of at least two.
# 
# 
# 
# **Example 1:**
# 
#     
#     
#     Input: intervals = [[1,3],[1,4],[2,5],[3,5]]
#     Output: 3
#     Explanation: Consider the set S = {2, 3, 4}.  For each interval, there are at least 2 elements from S in the interval.
#     Also, there isn't a smaller size set that fulfills the above condition.
#     Thus, we output the size of this set, which is 3.
#     
# 
# **Example 2:**
# 
#     
#     
#     Input: intervals = [[1,2],[2,3],[2,4],[4,5]]
#     Output: 5
#     Explanation: An example of a minimum sized set is {1, 2, 3, 4, 5}.
#     
# 
# 
# 
# **Constraints:**
# 
#   * `1 <= intervals.length <= 3000`
#   * `intervals[i].length == 2`
#   * `0 <= ai < bi <= 108`
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
