leetcode Day24----array.easy

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于 2019-05-02 21:37:07 发布

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博客围绕在给定整数数组中查找最大元素是否至少为其他数两倍展开。若满足条件，返回最大元素索引，否则返回 -1。给出了示例及数组长度和元素范围限制，还展示了用 C 语言和 Python3 实现该功能的运行情况。

Largest Number At Least Twice of Others

In a given integer array nums, there is always exactly one largest element.

Find whether the largest element in the array is at least twice as much as every other number in the array.

If it is, return the index of the largest element, otherwise return -1.

Example 1:

Input: nums = [3, 6, 1, 0]
Output: 1
Explanation: 6 is the largest integer, and for every other number in the array x,
6 is more than twice as big as x. The index of value 6 is 1, so we return 1.

Example 2:

Input: nums = [1, 2, 3, 4]
Output: -1
Explanation: 4 isn’t at least as big as twice the value of 3, so we return -1.

Note:

nums will have a length in the range [1, 50].
Every nums[i] will be an integer in the range [0, 99].

C语言

int dominantIndex(int* nums, int numsSize){
    int max,sec,i=2,j;
    if(numsSize<2){return 0;}
    else{
        if(nums[0]>nums[1]){max=nums[0];sec=nums[1];j=0;}
        else{max=nums[1];sec=nums[0];j=1;}
        while(i<numsSize){if(nums[i]>max){sec=max;max=nums[i];j=i;}else if(nums[i]>sec){sec=nums[i];}++i;}
        if(max>=2*sec){return j;}
        else return -1;
    }
    return 0;
}

Success
Details
Runtime: 4 ms, faster than 91.08% of C online submissions for Largest Number At Least Twice of Others.
Memory Usage: 6.9 MB, less than 100.00% of C online submissions for Largest Number At Least Twice of Others.

python3

还是熟悉的heapq。。

import heapq
class Solution:
    def dominantIndex(self, nums: List[int]) -> int:
        if(len(nums)<2):
            return 0
        a=heapq.nlargest(3, nums)
        if(2*a[1]>a[0]):
            return -1
        else:
            return nums.index(a[0])

Success
Details
Runtime: 40 ms, faster than 62.05% of Python3 online submissions for Largest Number At Least Twice of Others.
Memory Usage: 13.1 MB, less than 6.82% of Python3 online submissions for Largest Number At Least Twice of Others.