给定两个整数N和K。该任务是打印由小写的英语字母组成的长度为N的词典上最小的字符串,以使字符串的字符总和等于K ,其中‘a’= 1,’b’= 2,’c’= 3 ,…..和’z’= 26 。
例子:
Input: N = 5, K = 42
Output: aaamz
“aaany”, “babmx”, “aablz” etc. are also valid strings
but “aaamz” is the lexicographically smallest.
Input: N = 3, K = 25
Output: aaw
方法:
- 初始化大小为N的char数组,并用‘a’填充所有元素。
- 从数组的末尾开始遍历,如果K≥26 ,则用‘z’替换数组的元素,或者用ASCII值(K + 97-1)的字符替换它。
- 同时,用替换的元素值减小K的值,即a = 1 , b = 2 , c = 3 ,…, z = 26 。
- 另外,请注意,我们要减去当前元素之前的前一个元素值,即(总“ a”),并在for循环结束之前添加该值。
- 检查K <0条件并中断for循环。
- 返回由char数组的元素形成的新字符串作为答案。
下面是上述方法的实现:
C++
// C++ implementation of the approach
#include
using namespace std;
// Function to return the lexicographically
// smallest string of length n that
// satisfies the given condition
string lexo_small(int n, int k)
{
string arr = "";
for(int i = 0; i < n; i++)
arr += 'a';
// Iteration from the last position
// in the array
for (int i = n - 1; i >= 0; i--)
{
k -= i;
// If k is a positive integer
if (k >= 0)
{
// 'z' needs to be inserted
if (k >= 26)
{
arr[i] = 'z';
k -= 26;
}
// Add the required character
else
{
char c= (char)(k + 97 - 1);
arr[i] = c;
k -= arr[i] - 'a' + 1;
}
}
else
break;
k += i;
}
return arr;
}
// Driver code
int main()
{
int n = 5, k = 42;
string arr = lexo_small(n, k);
cout << arr;
}
// This code is contributed by Mohit Kumar
Java
// Java implementation of the approach
import java.util.Arrays;
public class Main {
// Function to return the lexicographically
// smallest string of length n that
// satisfies the given condition
public static char[] lexo_small(int n, int k)
{
char arr[] = new char[n];
Arrays.fill(arr, 'a');
// Iteration from the last position
// in the array
for (int i = n - 1; i >= 0; i--) {
k -= i;
// If k is a positive integer
if (k >= 0) {
// 'z' needs to be inserted
if (k >= 26) {
arr[i] = 'z';
k -= 26;
}
// Add the required character
else {
arr[i] = (char)(k + 97 - 1);
k -= arr[i] - 'a' + 1;
}
}
else
break;
k += i;
}
return arr;
}
// Driver code
public static void main(String[] args)
{
int n = 5, k = 42;
char arr[] = lexo_small(n, k);
System.out.print(new String(arr));
}
}
Python3
# Python implementation of the approach
# Function to return the lexicographically
# smallest string of length n that
# satisfies the given condition
def lexo_small(n, k):
arr = "";
for i in range(n):
arr += 'a';
# Iteration from the last position
# in the array
for i in range(n-1,-1,-1):
k -= i;
# If k is a positive integer
if (k >= 0):
# 'z' needs to be inserted
if (k >= 26):
arr = arr[:i] + 'z' + arr[i+1:];
k -= 26;
# Add the required character
else:
c= (k + 97 - 1);
arr = arr[:i] + chr(c) + arr[i+1:];
k -= ord(arr[i]) - ord('a') + 1;
else:
break;
k += i;
return arr;
# Driver code
if __name__ == '__main__':
n = 5; k = 42;
arr = lexo_small(n, k);
print(arr);
# This code contributed by PrinciRaj1992
C#
// C# implementation of the approach
using System;
class GFG
{
// Function to return the lexicographically
// smallest string of length n that
// satisfies the given condition
public static char[] lexo_small(int n, int k)
{
char []arr = new char[n];
int i;
for(i = 0; i < n; i++)
arr[i] = 'a' ;
// Iteration from the last position
// in the array
for (i = n - 1; i >= 0; i--)
{
k -= i;
// If k is a positive integer
if (k >= 0)
{
// 'z' needs to be inserted
if (k >= 26)
{
arr[i] = 'z';
k -= 26;
}
// Add the required character
else
{
arr[i] = (char)(k + 97 - 1);
k -= arr[i] - 'a' + 1;
}
}
else
break;
k += i;
}
return arr;
}
// Driver code
public static void Main()
{
int n = 5, k = 42;
char []arr = lexo_small(n, k);
Console.WriteLine(new string(arr));
}
}
// This code is contributed by AnkitRai01
输出:
aaamz