烙饼排序

 

#include <stdio.h>
// print the array
int printArr(int* arr, int length)
{
    int i = 0;
    for(i=0;i<length;i++)
        printf("%d	",arr[i]);
    printf("
");
}
// swap 2 value
void swapValue(int *a, int * b)
{
    int temp = 0;
    temp = *a;
    *a = *b;
    *b = temp;
}
// check whether the array is sorted
int isDone(int * arr, int length)
{
    while(--length>=1)
    {
        if(arr[length]>arr[length-1])
            return 0;
    }
    return 1;
}
// find the biggest value's index
int findMaxIndex(int* arr, int length)
{
    int i = 0;
    int standBy = arr[0];
    while(length--)
    {
        if(standBy < arr[length])
        {
            standBy = arr[length];
            i = length;
        }
    }
    return i;
}
// reverse the part of the array from the start position
int reversePart(int* arr, int start, int length)
{
    int end = length-1;
    while(start<=end)
    {
        swapValue(&arr[start],&arr[end]);
        start++;
        end--;
    }
}
// core algorithm
// 1. find the biggest value's index
// 2. check if the index is at the head of the array
//    true : enter the next loop
//    false : go to 3 step
// 3. check if the index is at the end of the array
//    true : go to 4 step
//    false : reverse the part -- get the biggest value to the end of the array
// 4. reverse the selected part of the array
// 5. check whether the array is sorted
//    true : break the loop
//    false : enter the next loop
void biscuitSort(int* arr, int length)
{
    int start = 0;
    int maxIndex = 0;
    for(start = 0; start < length; start++)
    {
        maxIndex = findMaxIndex(arr+start,length-start);
        if(maxIndex != 0)
        {
            if(maxIndex != length-start-1)
            {
                reversePart(arr+start,maxIndex,length-start);
                printArr(arr,length);
            }
            reversePart(arr+start,0,length-start);
            printArr(arr,length);
            if(isDone(arr,length))
                break;
        }
    }
}
 
int main()
{
    int arr[]= {7,1,2,5,4};
    printArr(arr, sizeof(arr)/sizeof(int));
    biscuitSort(arr, sizeof(arr)/sizeof(int));
    return 0;
}