LeetCode: 34. 搜索范围 #79

class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        int targetIndex = findTarget(nums, target);
        if (targetIndex == -1) {
            return {-1, -1};
        }
        int first = targetIndex;
        while (first >= 0) {
            if (nums[first] == target) {
                first -= 1;
            } else {
                break;
            }
        }
        int last = targetIndex;
        while (last < nums.size()) {
            if (nums[last] == target) {
                last += 1;
            } else {
                break;
            }
        }
        return {first + 1, last - 1};
    }
    
    int findTarget(vector<int>& nums, int target) {
        int first = 0, last = nums.size();

        while (first != last) {
            const int mid = (first + last) / 2;
            if (nums[mid] == target) {
                return mid;
            }
            
            if (nums[first] <= nums[mid]) {
                if (nums[first] <= target && target < nums[mid]) {
                    last = mid;
                } else {
                    first = mid + 1;
                }
            } else {
                if (nums[mid] < target && target <= nums[last - 1]) {
                    first = mid + 1;
                } else {
                    last = mid;
                }
            }
        }
        
        return -1;
    }
};