先递增后递减数组找第一个出现的目标数字

先找出最大值的第一个下标
再分两次 二分
找的是第一次出现的下标

public int findFirstOne(int[] nums, int target) {
        if (nums.length == 0) return -1;

        int n = nums.length;
        
        int maxNumIndex = findMaxNumIndex(nums);
        
        int idx1 = findTargetAscend(nums, 0, maxNumIndex, target);
        if (idx1 != -1) return idx1;

        int idx2 = findTargetDescend(nums, maxNumIndex, n - 1, target);
        return idx2;
    }

    private int findMaxNumIndex(int[] nums) {
        int lo = 0, hi = nums.length-1;

        while (lo < hi) {
            int mid = lo + (hi - lo) / 2;
            if      (nums[mid] < nums[mid+1]) lo = mid + 1;
            else if (nums[mid] > nums[mid+1]) hi = mid;
            else {
                if (nums[lo] < nums[hi]) lo++;
                else                     hi--;
            }
        }
        return lo;
    }

    private int findTargetAscend(int[] nums, int lo, int hi, int target) {
        while (lo <= hi) {
            int mid = lo + (hi - lo) / 2;

            if      (target > nums[mid]) lo = mid + 1;
            else if (target < nums[mid]) hi = mid - 1;
            else {
                while (mid >= 0 && nums[mid] == target) mid--;

                if (mid < 0) return 0;
                else         return mid+1;
            }
        }
        return -1;
    }

    private int findTargetDescend(int[] nums, int lo, int hi, int target) {
        int start = lo;

        while (lo <= hi) {
            int mid = lo + (hi - lo) / 2;

            if      (target > nums[mid]) hi = mid - 1;
            else if (target < nums[mid]) lo = mid + 1;
            else {
                while (mid >= start && nums[mid] == target) mid--;

                if (mid < start) return start;
                else             return mid+1;
            }
        }
        return -1;
    }