给定字符串str ,任务是检查该字符串是否为反向双音字符串。如果字符串str是反向Bitonic字符串,则打印“ YES” 。否则,打印“否” 。
A Reverse Bitonic String is a string in which the characters are arranged in decreasing order followed by increasing order of their ASCII values.
例子:
Input: str = “zyxbcd”
Output: YES
Explanation:
In the above string, the ASCII values first decreases {z, y, x} and then increases {b, c, d}.
Input: str = “abcdwef”
Output: NO
方法:
为了解决这个问题,遍历字符串并检查字符串的字符的ASCII值以下任何模式:
- 严格增加。
- 严格减少。
- 严格减少,然后严格增加。
请按照以下步骤解决问题:
- 遍历字符串,对于每个字符,检查下一个字符的ASCII值是否小于当前字符的ASCII值。
- 如果在任何时候下一个字符的ASCII值大于当前字符的ASCII值,请中断循环。
- 现在从该索引开始遍历,对于每个字符,检查下一个字符的ASCII值是否大于当前字符的ASCII值。
- 如果在到达数组末尾之前的任何时候,下一个字符的ASCII值小于当前字符的ASCII值,则打印“ NO”并中断循环。
- 如果成功遍历了整个字符串,请打印“ YES” 。
下面是上述方法的实现:
C++
// C++ program to implement
// the above approach
#include
using namespace std;
// Function to check if the given
// string is reverse bitonic
int checkReverseBitonic(string s)
{
int i, j;
// Check for decreasing sequence
for (i = 1; i < s.size(); i++) {
if (s[i] < s[i - 1])
continue;
if (s[i] >= s[i - 1])
break;
}
// If end of string has
// been reached
if (i == s.size() - 1)
return 1;
// Check for increasing sequence
for (j = i + 1; j < s.size();
j++) {
if (s[j] > s[j - 1])
continue;
if (s[j] <= s[j - 1])
break;
}
i = j;
// If the end of string
// hasn't been reached
if (i != s.size())
return 0;
// If the string is
// reverse bitonic
return 1;
}
// Driver Code
int main()
{
string s = "abcdwef";
(checkReverseBitonic(s) == 1)
? cout << "YES"
: cout << "NO";
return 0;
}
Java
// Java program to implement
// the above approach
class GFG{
// Function to check if the given
// string is reverse bitonic
static int checkReverseBitonic(String s)
{
int i, j;
// Check for decreasing sequence
for(i = 1; i < s.length(); i++)
{
if (s.charAt(i) < s.charAt(i - 1))
continue;
if (s.charAt(i) >= s.charAt(i - 1))
break;
}
// If end of string has
// been reached
if (i == s.length() - 1)
return 1;
// Check for increasing sequence
for(j = i + 1; j < s.length(); j++)
{
if (s.charAt(j) > s.charAt(j - 1))
continue;
if (s.charAt(j) <= s.charAt(j - 1))
break;
}
i = j;
// If the end of string
// hasn't been reached
if (i != s.length())
return 0;
// If the string is
// reverse bitonic
return 1;
}
// Driver Code
public static void main(String []args)
{
String s = "abcdwef";
if(checkReverseBitonic(s) == 1)
System.out.println("YES");
else
System.out.println("NO");
}
}
// This code is contributed by grand_master
Python3
# Python3 program to implement
# the above approach
# Function to check if the given
# string is reverse bitonic
def checkReverseBitonic(s):
i = 0
j = 0
# Check for decreasing sequence
for i in range(len(s)):
if (s[i] < s[i - 1]) :
continue;
if (s[i] >= s[i - 1]) :
break;
# If end of string has been reached
if (i == len(s)-1) :
return 1;
# Check for increasing sequence
for j in range(i + 1, len(s)):
if (s[j] > s[j - 1]) :
continue;
if (s[j] <= s[j - 1]) :
break;
i = j;
# If the end of string hasn't
# been reached
if (i != len(s)) :
return 0;
# If reverse bitonic
return 1;
# Given string
s = "abcdwef"
# Function Call
if(checkReverseBitonic(s) == 1) :
print("YES")
else:
print("NO")
C#
// C# program to implement
// the above approach
using System;
class GFG{
// Function to check if the given
// string is reverse bitonic
static int checkReverseBitonic(String s)
{
int i, j;
// Check for decreasing sequence
for(i = 1; i < s.Length; i++)
{
if (s[i] < s[i - 1])
continue;
if (s[i] >= s[i - 1])
break;
}
// If end of string has
// been reached
if (i == s.Length - 1)
return 1;
// Check for increasing sequence
for(j = i + 1; j < s.Length; j++)
{
if (s[j] > s[j - 1])
continue;
if (s[j] <= s[j - 1])
break;
}
i = j;
// If the end of string
// hasn't been reached
if (i != s.Length)
return 0;
// If the string is
// reverse bitonic
return 1;
}
// Driver Code
public static void Main(String []args)
{
String s = "abcdwef";
if(checkReverseBitonic(s) == 1)
Console.WriteLine("YES");
else
Console.WriteLine("NO");
}
}
// This code is contributed by 29AjayKumar
Javascript
输出:
NO
时间复杂度: O(N)
辅助空间: O(1)
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