LeetCode知识点总结 - 1893

LeetCode 1893. Check if All the Integers in a Range Are Covered

题目

You are given a 2D integer array ranges and two integers left and right. Each ranges[i] = [starti, endi] represents an inclusive interval between starti and endi.

Return true if each integer in the inclusive range [left, right] is covered by at least one interval in ranges. Return false otherwise.

An integer x is covered by an interval ranges[i] = [starti, endi] if starti <= x <= endi.

思路

如果left在一个range之间，left到这个range的最大值（inclusive）都被这个range包括，所以把left更新成range的最大值+1，直到iterate完所有range。如果left大于right，说明原来的left和right之间的所有值都已经被cover，返回true。

答案

public boolean isCovered(int[][] ranges, int left, int right) {
        Arrays.sort(ranges, (x,y)->x[0]-y[0]);
        for(int[] range: ranges) 
            if(left >= range[0] && left <= range[1])
                left = range[1] + 1;
        return left > right;
}