| # | Problem | Pass Rate (passed user / total user) |
|---|---|---|
| 13011 | Palindrome Detection (hard version) |
|
| 13012 | Bubble Sort |
|
Description
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A palindrome is a word like “deed” or “level”, which remains the same when you spell it backward.
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Write a program that inputs a word that terminates with a period '.' and determines whether or not the word is a palindrome.
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Each input word's length is at least 1 and there is no maximum limit for its length. You must use DYNAMIC ARRAYs to do this task.
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(Hint: You may define an array of size 20 to take the input first. If it's not enough, double its size to allow more input.)
Input
String of characters that terminates with a period '.'
Output
"a palindrome\n" or "not a palindrome\n"
Sample Input Download
Sample Output Download
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Description
Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements and swaps them if they are in the wrong order. The pass through the list is repeated until the list is sorted. The algorithm, which is a comparison sort, is named for the way smaller or larger elements "bubble" to the top of the list.
You must implement these function prototypes：
void bubble_sort(int arr[], int len);
void swap(int *x, int *y);
All you need to submit are：
void bubble_sort(int arr[], int len){
...
...
}
void swap(int *x, int *y){
...
...
}
Step-by-step example
Take an array of numbers "5 1 4 2 8", and sort the array from lowest number to greatest number using bubble sort. In each step, elements written in bold are being compared. Three passes will be required;
( 5 1 4 2 8 ) → ( 1 5 4 2 8 ), Here, algorithm compares the first two elements, and swaps since 5 > 1.
( 1 5 4 2 8 ) → ( 1 4 5 2 8 ), Swap since 5 > 4
( 1 4 5 2 8 ) → ( 1 4 2 5 8 ), Swap since 5 > 2
( 1 4 2 5 8 ) → ( 1 4 2 5 8 ), Now, since these elements are already in order (8 > 5), algorithm does not swap them.
( 1 4 2 5 8 ) → ( 1 4 2 5 8 )
( 1 4 2 5 8 ) → ( 1 2 4 5 8 ), Swap since 4 > 2
( 1 2 4 5 8 ) → ( 1 2 4 5 8 )
( 1 2 4 5 8 ) → ( 1 2 4 5 8 )
Now, the array is already sorted, but the algorithm does not know if it is completed. The algorithm needs one whole pass without any swap to know it is sorted.
( 1 2 4 5 8 ) → ( 1 2 4 5 8 )
( 1 2 4 5 8 ) → ( 1 2 4 5 8 )
( 1 2 4 5 8 ) → ( 1 2 4 5 8 )
( 1 2 4 5 8 ) → ( 1 2 4 5 8 )