Leetcode 题目解析之 Search for a Range

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ruochen

发布于 2022-01-09 11:48:19

1.2K0

发布于 2022-01-09 11:48:19

文章被收录于专栏：若尘的技术专栏

Given a sorted array of integers, find the starting and ending position of a given target value.

Your algorithm's runtime complexity must be in the order of O(log n).

If the target is not found in the array, return -1, -1.

For example,

Given 5, 7, 7, 8, 8, 10 and target value 8,

return 3, 4.

    public int[] searchRange(int[] nums, int target) {
        int l = 0, r = nums.length;
        while (l < r) {
            int m = l + (r - l) / 2;
            if (nums[m] == target) {
                int s = m, e = m;
                while (s - 1 >= 0 && nums[s - 1] == target) {
                    s--;
                }
                while (e + 1 < nums.length && nums[e + 1] == target) {
                    e++;
                }
                return new int[] { s, e };
            } else if (nums[m] > target) {
                r = m;
            } else {
                l = m + 1;
            }
        }
        return new int[] { -1, -1 };
    }

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algorithm