找出给定数字能组成的最大数字
给定一个代表数字的整数数组 arr[]。任务是编写一个程序，用这些数字产生最大可能的数字。 注:数组中的数字在 0 到 9 之间。即 0 < arr[i] < 9。 T4【示例】T5:
Input : arr[] = {4, 7, 9, 2, 3}
Output : Largest number: 97432
Input : arr[] = {8, 6, 0, 4, 6, 4, 2, 7}
Output : Largest number: 87664420
朴素方法:朴素方法是将给定的数字数组按照降序排序，然后使用数组中的数字组成数字，保持数字在数字中的顺序与排序后的数组相同。 时间复杂度:O(N logN)，其中 N 为位数。 以下是上述思路的实现:
C++
// C++ program to generate largest possible
// number with given digits
#include <bits/stdc++.h>
using namespace std;
// Function to generate largest possible
// number with given digits
int findMaxNum(int arr[], int n)
{
// sort the given array in
// descending order
sort(arr, arr+n, greater<int>());
int num = arr[0];
// generate the number
for(int i=1; i<n; i++)
{
num = num*10 + arr[i];
}
return num;
}
// Driver code
int main()
{
int arr[] = {1, 2, 3, 4, 5, 0};
int n = sizeof(arr)/sizeof(arr[0]);
cout<<findMaxNum(arr,n);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to generate largest
// possible number with given digits
import java.*;
import java.util.Arrays;
class GFG
{
// Function to generate largest
// possible number with given digits
static int findMaxNum(int arr[], int n)
{
// sort the given array in
// ascending order and then
// traverse into descending
Arrays.sort(arr);
int num = arr[0];
// generate the number
for(int i = n - 1; i >= 0; i--)
{
num = num * 10 + arr[i];
}
return num;
}
// Driver code
public static void main(String[] args)
{
int arr[] = {1, 2, 3, 4, 5, 0};
int n = arr.length;
System.out.println(findMaxNum(arr, n));
}
}
// This code is contributed by mits
Python 3
# Python3 program to generate largest possible
# number with given digits
# Function to generate largest possible
# number with given digits
def findMaxNum(arr,n) :
# sort the given array in
# descending order
arr.sort(reverse = True)
# initialize num with starting
# element of an arr
num = arr[0]
# generate the number
for i in range(1,n) :
num = num * 10 + arr[i]
return num
# Driver code
if __name__ == "__main__" :
arr = [1,2,3,4,5,0]
n = len(arr)
print(findMaxNum(arr,n))
C
// C# program to generate largest
// possible number with given digits
using System;
public class GFG{
// Function to generate largest
// possible number with given digits
static int findMaxNum(int []arr, int n)
{
// sort the given array in
// ascending order and then
// traverse into descending
Array.Sort(arr);
int num = arr[0];
// generate the number
for(int i = n - 1; i >= 0; i--)
{
num = num * 10 + arr[i];
}
return num;
}
// Driver code
static public void Main (){
int []arr = {1, 2, 3, 4, 5, 0};
int n = arr.Length;
Console.WriteLine(findMaxNum(arr, n));
}
}
// This code is contributed by Sachin..
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program to generate
// largest possible number
// with given digits
// Function to generate
// largest possible number
// with given digits
function findMaxNum(&$arr, $n)
{
// sort the given array
// in descending order
rsort($arr);
$num = $arr[0];
// generate the number
for($i = 1; $i < $n; $i++)
{
$num = $num * 10 + $arr[$i];
}
return $num;
}
// Driver code
$arr = array(1, 2, 3, 4, 5, 0);
$n = sizeof($arr);
echo findMaxNum($arr,$n);
// This code is contributed
// by ChitraNayal
?>
java 描述语言
<script>
// Javascript program to generate largest possible
// number with given digits
// Function to generate largest possible
// number with given digits
function findMaxNum(arr, n)
{
// sort the given array in
// descending order
arr.sort(function(a,b){return b-a;});
var num = arr[0];
// generate the number
for(var i=1; i<n; i++)
{
num = num*10 + arr[i];
}
return num;
}
// Driver code
var arr = [1, 2, 3, 4, 5, 0];
var n = arr.length;
document.write(findMaxNum(arr,n));
</script>
Output:
543210
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