在给定的数字中使用一次交换操作可能得到的最大偶数
给定一个字符串形式的奇数，任务是从给定的数字中产生最大的偶数，并且只允许您执行一次交换操作。 例:
Input : 1235785
Output :1535782
Swap 2 and 5.
Input : 536425
Output : 536524
Swap 4 and 5 to make the largest even number.
- 在最后一个索引处找到小于或等于奇数的第一个偶数。
- 如果找到，交换两个值。否则与字符串中的最后一个偶数交换。
- 如果无法做到平衡，打印给定的字符串。
C++
// C++ program for above implementation
#include <bits/stdc++.h>
using namespace std;
// Make the largest even number
string makeEven(string str)
{
int n = str.length();
int even = INT_MAX, index;
// Start traversing the string
for (int i = 0; i < n - 1; i++) {
// Find the even number
if ((str[i] - '0') % 2 == 0) {
even = (str[i] - '0');
index = i;
}
// Check if current even is equal to
// or less than the odd number
if (even <= (str[n - 1] - '0'))
break;
}
// Return original string if there is no
// even value
if (even == INT_MAX)
return str;
// Swap even and odd value
swap(str[index], str[n - 1]);
return str;
}
// Driver code
int main()
{
string str = "1356425";
cout << makeEven(str);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program for above implementation
class GFG {
// Make the largest even number
static char[] makeEven(String string) {
char []str = string.toCharArray();
int n = str.length;
int even = Integer.MAX_VALUE, index = 0;
// Start traversing the String
for (int i = 0; i < n - 1; i++) {
// Find the even number
if ((str[i] - '0') % 2 == 0) {
even = (str[i] - '0');
index = i;
}
// Check if current even is equal to
// or less than the odd number
if (even <= (str[n-1] - '0')) {
break;
}
}
// Return original String if there is no
// even value
if (even == Integer.MAX_VALUE) {
return str;
}
// Swap even and odd value
swap(str,index, n - 1);
return str;
}
static void swap(char[] str,int index1,int index2){
char temp = str[index1];
str[index1] = str[index2];
str[index2] =temp;
}
// Driver code
public static void main(String[] args) {
String str = "1356425";
System.out.print(makeEven(str));
}
}
/*This code is contributed by PrinciRaj1992*/
Python 3
# Python3 code for the above implementation
import sys
# Make the largest even number
def makeEven(arr, n):
# index to first even no,if any
first_e_i = -1
# index to last even no, if any
last_e_i = -1
# index to last no
last_n_i = n - 1
# Start traversing the String
for i in range(n):
# if it finds any first even no less
# than last digit then break the loop
if (int(arr[i]) % 2 == 0 and
int(arr[i]) < int(arr[last_n_i])):
first_e_i = i
break
# it finds last even no
if int(arr[i]) % 2 == 0:
last_e_i = i
if first_e_i != -1:
# swap even and odd value
(arr[first_e_i],
arr[last_n_i]) = (arr[last_n_i],
arr[first_e_i])
return arr
if first_e_i == -1 and last_e_i != -1:
# swap even and odd value
(arr[last_e_i],
arr[last_n_i]) = (arr[last_n_i],
arr[last_e_i])
return arr
# Return original String if there is
# no even number
return arr
# Driver Code
if __name__=='__main__':
string="1356425"
result = "".join(makeEven(list(string),
len(list(string))))
print(result)
# This code is contributed
# by Vikash Kumar 37
C
// C# implementation of above approach
using System;
public class GFG {
// Make the largest even number
static char[] makeEven(String str1) {
char []str = str1.ToCharArray();
int n = str.Length;
int even = int.MaxValue, index = 0;
// Start traversing the String
for (int i = 0; i < n - 1; i++) {
// Find the even number
if ((str[i] - '0') % 2 == 0) {
even = (str[i] - '0');
index = i;
}
// Check if current even is equal to
// or less than the odd number
if (even <= (str[n-1] - '0')) {
break;
}
}
// Return original String if there is no
// even value
if (even == int.MaxValue) {
return str;
}
// Swap even and odd value
swap(str,index, n - 1);
return str;
}
static void swap(char[] str,int index1,int index2){
char temp = str[index1];
str[index1] = str[index2];
str[index2] =temp;
}
// Driver code
public static void Main() {
String str = "1356425";
Console.WriteLine(makeEven(str));
}
}
/*This code is contributed by PrinciRaj1992*/
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program for above implementation
// Make the largest even number
function makeEven($str)
{
$n = strlen($str);
$even = PHP_INT_MAX; $index;
// Start traversing the string
for ($i = 0; $i < $n - 1; $i++)
{
// Find the even number
if (($str[$i] - '0') % 2 == 0)
{
$even = ($str[$i] - '0');
$index = $i;
}
// Check if current even is
// equal to or less than
// the odd number
if ($even <= ($str[$n - 1] - '0'))
break;
}
// Return original string if
// there is no even value
if ($even == PHP_INT_MAX)
return $str;
//swap the number
list($str[$index],
$str[$n - 1]) = array($str[$n - 1],
$str[$index]);
return $str;
}
// Driver code
$str = "1356425";
echo makeEven($str);
// This code is contributed by ajit
?>
java 描述语言
<script>
// Javascript program for above implementation
// Make the largest even number
function makeEven(string) {
let str = string.split('');
let n = str.length;
let even = Number.MAX_VALUE, index = 0;
// Start traversing the String
for (let i = 0; i < n - 1; i++) {
// Find the even number
if ((str[i].charCodeAt() - '0'.charCodeAt()) % 2 == 0) {
even = (str[i] - '0');
index = i;
}
// Check if current even is equal to
// or less than the odd number
if (even <= (str[n-1].charCodeAt() - '0'.charCodeAt())) {
break;
}
}
// Return original String if there is no
// even value
if (even == Number.MAX_VALUE) {
return str;
}
// Swap even and odd value
swap(str,index, n - 1);
return str.join("");
}
function swap(str, index1, index2)
{
let temp = str[index1];
str[index1] = str[index2];
str[index2] =temp;
}
let str = "1356425";
document.write(makeEven(str));
</script>
输出:
1356524
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