162. 寻找峰值

class Solution {
  public int findPeakElement(int[] nums) {
      //nums[-1] nums[n] 是无穷  也就是说需要看nums[0] nums[n-1]
      int n =  nums.length;
      if(n==0||n==1)return 0;
      if(nums[0]>nums[1])return 0;
      if(nums[n-1]>nums[n-2])return n-1;
      for(int i = 1 ; i < n-1 ; i++) {
          if(nums[i]>nums[i-1]&&nums[i]>nums[i+1])
              return i;
      }
      return 0;
  }
}

class Solution {
    public int findPeakElement(int[] nums) {
      //nums[-1] nums[n] 是无穷  也就是说需要看nums[0] nums[n-1]
      int n =  nums.length;
      if(n==0)return 0;
      int l = 0;
      int r = n-1;
      while(l<r) {
          int mid = (l + r)/2;
          if (nums[mid] > nums[mid + 1])
              r = mid;
          else
              l = mid + 1;
      }
      return l;
  }
}