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1288.remove-covered-intervals.cpp
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46 lines (44 loc) · 1.22 KB
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// Tag: Array, Sorting
// Time: O(NlogN)
// Space: O(1)
// Ref: -
// Note: -
// Given an array intervals where intervals[i] = [li, ri] represent the interval [li, ri), remove all intervals that are covered by another interval in the list.
// The interval [a, b) is covered by the interval [c, d) if and only if c <= a and b <= d.
// Return the number of remaining intervals.
//
// Example 1:
//
// Input: intervals = [[1,4],[3,6],[2,8]]
// Output: 2
// Explanation: Interval [3,6] is covered by [2,8], therefore it is removed.
//
// Example 2:
//
// Input: intervals = [[1,4],[2,3]]
// Output: 1
//
//
// Constraints:
//
// 1 <= intervals.length <= 1000
// intervals[i].length == 2
// 0 <= li < ri <= 105
// All the given intervals are unique.
//
//
class Solution {
public:
int removeCoveredIntervals(vector<vector<int>>& intervals) {
sort(intervals.begin(), intervals.end(), [](vector<int> &a, vector<int> &b) {
return a[0] < b[0] || (a[0] == b[0] && a[1] > b[1]);
});
int right = 0;
int res = 0;
for (auto &inter: intervals) {
res += inter[1] > right;
right = max(right, inter[1]);
}
return res;
}
};