参考链接： Python Set intersection()
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 size at least 2.
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}.
Note:
intervals will have length in range [1, 3000]. intervals[i] will have length 2, representing some integer interval. intervals[i][j] will be an integer in [0, 10^8].
class Solution {
public int intersectionSizeTwo(int[][] intervals) {
Arrays.sort(intervals, (a, b) ->
a[0] != b[0] ? a[0]-b[0] : b[1]-a[1]);
int[] todo = new int[intervals.length];
Arrays.fill(todo, 2);
int ans = 0, t = intervals.length;
while (--t >= 0) {
int s = intervals[t][0];
int e = intervals[t][1];
int m = todo[t];
for (int p = s; p < s m; p) {
for (int i = 0; i <= t; i)
if (todo[i] > 0 && p <= intervals[i][1])
todo[i]--;
ans ;
}
}
return ans;
}
}
