# 查找數組中最大的三個元素 > 原文： [https://www.geeksforgeeks.org/find-the-largest-three-elements-in-an-array/](https://www.geeksforgeeks.org/find-the-largest-three-elements-in-an-array/) 給定一個包含所有不同元素的數組，找到最大的三個元素。 預期時間復雜度為`O(n)`，額外空間為`O(1)`。 **示例**： ``` Input: arr[] = {10, 4, 3, 50, 23, 90} Output: 90, 50, 23 ``` 下面是算法： ``` 1) Initialize the largest three elements as minus infinite. first = second = third = -∞ 2) Iterate through all elements of array. a) Let current array element be x. b) If (x > first) { // This order of assignment is important third = second second = first first = x } c) Else if (x > second) { third = second second = x } d) Else if (x > third) { third = x } 3) Print first, second and third. ``` 下面是上述算法的實現。 ## C ``` #include <stdio.h> #include <limits.h> /* For INT_MIN */ /* Function to print three largest elements */ void print3largest(int arr[], int arr_size) { ????int i, first, second, third; ????/* There should be atleast three elements */ ????if (arr_size < 3) ????{ ????????printf(" Invalid Input "); ????????return; ????} ????third = first = second = INT_MIN; ????for (i = 0; i < arr_size ; i ++) ????{ ????????/* If current element is greater than first*/ ????????if (arr[i] > first) ????????{ ????????????third = second; ????????????second = first; ????????????first = arr[i]; ????????} ????????/* If arr[i] is in between first and second then update second? */ ????????else if (arr[i] > second) ????????{ ????????????third = second; ????????????second = arr[i]; ????????} ????????else if (arr[i] > third) ????????????third = arr[i]; ????} ????printf("Three largest elements are %d %d %d\n", first, second, third); } /* Driver program to test above function */ int main() { ????int arr[] = {12, 13, 1, 10, 34, 1}; ????int n = sizeof(arr)/sizeof(arr[0]); ????print3largest(arr, n); ????return 0; } /*This code is edited by Ayush Singla(@ayusin51)*/ ```