# 數組中的最大值，至少是其他元素的兩倍 > 原文： [https://www.geeksforgeeks.org/maximum-array-least-twice-elements/](https://www.geeksforgeeks.org/maximum-array-least-twice-elements/) 給定長度為 n 的整數數組。 我們的任務是返回 max 元素的索引，如果它的索引至少是數組中每個其他數字的兩倍。 如果 max 元素不滿足條件，則返回-1。 **示例**： ``` Input : arr = {3, 6, 1, 0} Output : 1 Here, 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. Input : arr = {1, 2, 3, 4} Output : -1 4 isn't at least as big as twice the value of 3, so we return -1. ``` **方法**：掃描數組以查找唯一的最大元素 **m** ，并跟蹤其索引 **maxIndex** 。 再次掃描數組。 如果我們發現 **x！= m** 與 **m < 2 * x** ，我們應該返回 **-1** 。 否則，我們應該返回 **maxIndex** 。 ## C++ ```cpp // CPP program for Maximum of // the array which is at least // twice of other elements of // the array. #include<bits/stdc++.h> using namespace std; // Function to find the? // index of Max element? // that satisfies the? // condition int findIndex(int arr[], int len) {? ????// Finding index of ????// max of the array ????int maxIndex = 0; ????for (int i = 0; i < len; ++i)? ????????if (arr[i] > arr[maxIndex]) ????????????maxIndex = i; ????// Returns -1 if the ????// max element is not? ????// twice of the i-th ????// element.? ????for (int i = 0; i < len; ++i)????????????? ????????if (maxIndex != i && ????????????arr[maxIndex] < 2 * arr[i]) ????????????return -1; ????return maxIndex; } // Driver function int main(){ ????int arr[] = {3, 6, 1, 0}; ????int len = sizeof(arr) / sizeof(arr[0]); ????cout<<(findIndex(arr, len)); } // This code is contributed by Smitha Dinesh Semwal ``` ## Java ```java // Java program for Maximum of the array // which is at least twice of other elements? // of the array. import java.util.*; import java.lang.*; class GfG { ????// Function to find the index of Max element ????// that satisfies the condition ????public static int findIndex(int[] arr) {???????? ????????// Finding index of max of the array ????????int maxIndex = 0; ????????for (int i = 0; i < arr.length; ++i)? ????????????if (arr[i] > arr[maxIndex]) ????????????????maxIndex = i; ????????// Returns -1 if the max element is not? ????????// twice of the i-th element.???????? ????????for (int i = 0; i < arr.length; ++i)????????????? ????????????if (maxIndex != i && arr[maxIndex] < 2 * arr[i]) ????????????????return -1; ????????return maxIndex; ????} ????// Driver function ????public static void main(String argc[]){ ????????int[] arr = new int[]{3, 6, 1, 0}; ????????System.out.println(findIndex(arr)); ????} } ``` ## Python3 ```py # Python 3 program for Maximum of? # the array which is at least twice?? # of other elements of the array. # Function to find the index of Max? # element that satisfies the condition def findIndex(arr):? ????# Finding index of max of the array ????maxIndex = 0 ????for i in range(0,len(arr)): ????????if (arr[i] > arr[maxIndex]): ????????????maxIndex = i ????# Returns -1 if the max element is not? ????# twice of the i-th element.????? ????for i in range(0,len(arr)):????? ????????if (maxIndex != i and? ????????????????arr[maxIndex] < (2 * arr[i])): ????????????return -1 ????return maxIndex # Driver code arr = [3, 6, 1, 0] print(findIndex(arr)) # This code is contributed by Smitha Dinesh Semwal ``` ## C# ```cs // C# program for Maximum of the array // which is at least twice of other elements? // of the array. using System; class GfG { ????// Function to find the index of Max element ????// that satisfies the condition ????public static int findIndex(int[] arr) {????? ????????// Finding index of max of the array ????????int maxIndex = 0; ????????for (int i = 0; i < arr.Length; ++i)? ????????????if (arr[i] > arr[maxIndex]) ????????????????maxIndex = i; ????????// Returns -1 if the max element is not? ????????// twice of the i-th element.? ????????for (int i = 0; i < arr.Length; ++i)????????? ????????????if (maxIndex != i && arr[maxIndex] < 2 * arr[i]) ????????????????return -1; ????????return maxIndex; ????} ????// Driver function ????public static void Main() ????{ ????????int[] arr = new int[]{3, 6, 1, 0}; ????????Console.WriteLine(findIndex(arr)); ????} } // This code is contributed by vt_m. ``` ## PHP ```php <?php // PHP program for Maximum of // the array which is at least // twice of other elements of // the array. // Function to find the? // index of Max element? // that satisfies the? // condition function findIndex($arr, $len)? {? ????// Finding index of ????// max of the array ????$maxIndex = 0; ????for ( $i = 0; $i < $len; ++$i)? ????????if ($arr[$i] > $arr[$maxIndex]) ????????????$maxIndex = $i; ????// Returns -1 if the ????// max element is not? ????// twice of the i-th ????// element.? ????for ($i = 0; $i < $len; ++$i)????????????? ????????if ($maxIndex != $i and ????????????$arr[$maxIndex] < 2 * $arr[$i]) ????????????return -1; ????return $maxIndex; } // Driver Code $arr = array(3, 6, 1, 0); $len = count($arr); echo findIndex($arr, $len); // This code is contributed by anuj_67\. ?> ``` **輸出**： ``` 1 ``` **時間復雜度**： * * * * * *