检查给定数组是否完美
原文:https://www . geesforgeks . org/check-when-given-array-perfect-not/
有一个数组包含一些非负整数。检查数组是否完美。如果一个数组首先是严格递增的，然后是常数，最后是严格递减的，那么这个数组就叫做完美数组。三个部分中的任何一个都可以是空的。 例:
Input : arr[] = {1, 8, 8, 8, 3, 2}
Output : Yes
The array is perfect as it is first
increasing, then constant and finally
decreasing.
Input : arr[] = {1, 1, 2, 2, 1}
Output : No
The first part is not strictly increasing
Input : arr[] = {4, 4, 4, 4}
Output : Yes
方法是从左到右迭代数组，并增加 I(最初为 1)，而下一个元素严格来说比前面的更多。然后，从左向右迭代数组，并在两个相邻元素相等时增加 I。最后，从左到右迭代数组，并在下一个元素严格小于前一个元素时增加 I。如果我们通过这个过程到达终点，我们说这个阵列是完美的。
C++
// CPP program to check whether the given array
// is perfect or not.
#include <iostream>
using namespace std;
int checkUnimodal(int arr[], int n)
{
// Cover first strictly increasing part
int i = 1;
while (arr[i] > arr[i - 1] && i < n)
++i;
// Cover middle equal part
while (arr[i] == arr[i - 1] && i < n)
++i;
// Cover last decreasing part
while (arr[i] < arr[i - 1] && i < n)
++i;
// Return true if we reached end.
return (i == n);
}
int main()
{
int arr[] = { 1, 5, 5, 5, 4, 2 };
int n = sizeof(arr) / sizeof(arr[0]);
if (checkUnimodal(arr, n))
cout << "Yes" << endl;
else
cout << "No" << endl;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to check whether the given array
// is perfect or not.
import java.util.*;
class Node
{
static boolean checkUnimodal(int arr[], int n)
{
// Cover first strictly increasing part
int i = 1;
while (i < n && arr[i] > arr[i - 1])
++i;
// Cover middle equal part
while (i < n && arr[i] == arr[i - 1])
++i;
// Cover last decreasing part
while (i < n &&arr[i] < arr[i - 1])
++i;
// Return true if we reached end.
return (i == n);
}
// Driver code
public static void main(String[] args)
{
int arr[] = { 1, 5, 5, 5, 4, 2 };
int n = arr.length;
if (checkUnimodal(arr, n))
System.out.println("Yes");
else
System.out.println("No");
}
}
// This code is contributed by 29AjayKumar
Python 3
# Python 3 program to check whether the
# given array is perfect or not.
def checkUnimodal(arr, n):
# Cover first strictly increasing part
i = 1
while (i < n and arr[i] > arr[i - 1]):
i += 1
# Cover middle equal part
while (i < n and arr[i] == arr[i - 1]):
i += 1
# Cover last decreasing part
while (i < n and arr[i] < arr[i - 1]):
i += 1
# Return true if we reached end.
return (i == n)
# Driver Code
if __name__ == '__main__':
arr = [1, 5, 5, 5, 4, 2 ]
n = len(arr)
if (checkUnimodal(arr, n)):
print("Yes")
else:
print("No")
# This code is contributed by
# Surendra_Gangwar
C
// C# program to check whether the given array
// is perfect or not.
using System;
class GFG
{
static bool checkUnimodal(int []arr, int n)
{
// Cover first strictly increasing part
int i = 1;
while (i < n && arr[i] > arr[i - 1])
++i;
// Cover middle equal part
while (i < n && arr[i] == arr[i - 1])
++i;
// Cover last decreasing part
while (i < n &&arr[i] < arr[i - 1])
++i;
// Return true if we reached end.
return (i == n);
}
// Driver code
static public void Main ()
{
int []arr = { 1, 5, 5, 5, 4, 2 };
int n = arr.Length;
if (checkUnimodal(arr, n))
Console.Write("Yes");
else
Console.Write("No");
}
}
// This code is contributed by ajit..
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program to check whether the
// given array is perfect or not.
function check($arr, $n)
{
// Cover first strictly increasing part
$i = 1;
while ($arr[$i] > $arr[$i - 1] && $i < $n)
++$i;
// Cover middle equal part
while ($arr[$i] == $arr[$i - 1] && $i < $n)
++$i;
// Cover last decreasing part
while ($arr[$i] < $arr[$i - 1] && $i < $n)
++$i;
// Return true if we reached end
return ($i == $n);
}
// Driver Code
$arr = array(1, 5, 5, 5, 4, 2);
$n = sizeof($arr);
if (check($arr, $n))
echo "Yes";
else
echo "No";
// This code is contributed by Akanksha Rai
?>
java 描述语言
<script>
// Javascript program to check whether the given array
// is perfect or not.
function checkUnimodal(arr, n)
{
// Cover first strictly increasing part
let i = 1;
while (arr[i] > arr[i - 1] && i < n)
++i;
// Cover middle equal part
while (arr[i] == arr[i - 1] && i < n)
++i;
// Cover last decreasing part
while (arr[i] < arr[i - 1] && i < n)
++i;
// Return true if we reached end.
return (i == n);
}
let arr = [ 1, 5, 5, 5, 4, 2 ];
let n = arr.length;
if (checkUnimodal(arr, n))
document.write("YES");
else
document.write("NO");
</script>
输出:
YES
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