题解 | #寻找峰值#

using System;
using System.Collections.Generic;


class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param nums int整型一维数组
     * @return int整型
     */
    public int findPeakElement(List<int> nums) {
        // write code here
        if (nums == null || nums.Count == 0)
            return -1;
        if (nums.Count == 1)
            return 0;
        return ZBCZ(0, nums.Count - 1, nums);
    }

    public int ZBCZ(int nL, int nR, List<int> nums) {
        if (nL > nR)
            return -1;
        int nM = (nL + nR) / 2;
        int nML = nM - 1 >= 0 ? nums[nM - 1] : int.MinValue;
        int nMR = nM + 1 <= nums.Count - 1 ? nums[nM + 1] : int.MinValue;
        if (nums[nM] > nML && nums[nM] > nMR)
            return nM;
        int nLR = ZBCZ(nL, nM - 1, nums);
        if (nLR >= 0)
            return nLR;
        int nRR = ZBCZ(nM + 1, nR, nums);
        if (nRR >= 0)
            return nRR;
        else
            return -1;
    }
}