34、Search for a Range

Example

Given [5 , 7 , 7 , 8 , 8 ,10] target 8
return [3 , 4]

二分法即可

解法

public class Solution{
  public int[] searchRange(int[] nums, int target) {
    int[] res = {-1, -1};
    if (nums == null || nums.length == 0) {
        return res;
    }
    int left = 0;
    int right = nums.length - 1;
    while (left <= right) {
        int mid = left + (right - left) / 2;
        if (nums[mid] < target) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }
    int start = 0;
    int end = nums.length - 1;
    while(start <= end) {
        int mid = start + (end - start) / 2;
        if (nums[mid] > target) {
            end = mid - 1;
        } else {
            start = mid + 1;
        }
    }
    if (left <= end) {
        res[0] = left;
        res[1] = end;
    }
    return res;
  }
}