[LeetCode] 852. Peak Index in a Mountain Array

轉自LeetCode

Let's call an array A a mountain if the following properties hold:

• A.length >= 3
• There exists some 0 < i < A.length - 1

 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1]

Given an array that is definitely a mountain, return any i such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].

Example 1:

Input: [0,1,0]
Output: 1

Example 2:

Input: [0,2,1,0]
Output: 1

Note:

1. 3 <= A.length <= 10000
2. 0 <= A[i] <= 10^6
3. A is a mountain, as defined above.

<Solution>

想法如下

• 雖然題目解釋的很多，但就是找 array 裡面最大值的 index

code 如下

Java

	class Solution {
	public int peakIndexInMountainArray(int[] A) {
	int ans = -1, number = Integer.MIN_VALUE;
	for(int i = 0; i < A.length; i++) {
	if(A[i] > number) {
	ans = i;
	number = A[i];
	}
	}
	return ans;
	}
	}

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