120 - Stacks of Flapjacks

Uva

120 - Stacks of Flapjacks

 Stacks of Flapjacks 

Background

Stacks and Queues are often considered the bread and butter of data structures and find use in architecture, parsing, operating systems, and discrete event simulation. Stacks are also important in the theory of formal languages.

This problem involves both butter and sustenance in the form of pancakes rather than bread in addition to a finicky server who flips pancakes according to a unique, but complete set of rules.

The Problem

Given a stack of pancakes, you are to write a program that indicates how the stack can be sorted so that the largest pancake is on the bottom and the smallest pancake is on the top. The size of a pancake is given by the pancake's diameter. All pancakes in a stack have different diameters.

Sorting a stack is done by a sequence of pancake ``flips''. A flip consists of inserting a spatula between two pancakes in a stack and flipping (reversing) the pancakes on the spatula (reversing the sub-stack). A flip is specified by giving the position of the pancake on the bottom of the sub-stack to be flipped (relative to the whole stack). The pancake on the bottom of the whole stack has position 1 and the pancake on the top of a stack of n pancakes has position n.

A stack is specified by giving the diameter of each pancake in the stack in the order in which the pancakes appear.

For example, consider the three stacks of pancakes below (in which pancake 8 is the top-most pancake of the left stack):

         8           7           2         4           6           5         6           4           8         7           8           4         5           5           6         2           2           7

The stack on the left can be transformed to the stack in the middle via flip(3). The middle stack can be transformed into the right stack via the command flip(1).

The Input

The input consists of a sequence of stacks of pancakes. Each stack will consist of between 1 and 30 pancakes and each pancake will have an integer diameter between 1 and 100. The input is terminated by end-of-file. Each stack is given as a single line of input with the top pancake on a stack appearing first on a line, the bottom pancake appearing last, and all pancakes separated by a space.

The Output

For each stack of pancakes, the output should echo the original stack on one line, followed by some sequence of flips that results in the stack of pancakes being sorted so that the largest diameter pancake is on the bottom and the smallest on top. For each stack the sequence of flips should be terminated by a 0 (indicating no more flips necessary). Once a stack is sorted, no more flips should be made.

Sample Input

1 2 3 4 55 4 3 2 15 1 2 3 4

Sample Output

1 2 3 4 505 4 3 2 11 05 1 2 3 41 2 0

题目大意：

一行数据代表一叠薄煎饼，数据在前的表示叠在上面的薄煎饼，但按1-n排列煎饼时是按从下到上标号的，要求用锅产把他翻成小在上，大在下排列的。

当最大数恰好在1号位子时，无需更改，如果在最上面(即n号位)的话就直接1位置反转，否则的先反转到最上面的位子在翻向1号，其它以此类推。

注意：数据不是连续的，还可能有重复数据，数据大小在1-100之间，这是我连续WA了6次的发现...

#include <iostream>#include <cstdio>#include <algorithm>using namespace std;void exchange(int *a,int n){    for(int i=0;i<n;i++,n--)    {        a[i]^=a[n];        a[n]^=a[i];        a[i]^=a[n];    }}int main(){    int c,a[50],b[50],n=0,f=0;    while((c=getchar())!=EOF)    {        if(isdigit(c))//接受数字，数字范围在1～100;        {            a[n]=b[n]=a[n]*f+c-'0';            f=10;        }        else        {            if(f)                n++;            f=0;        }        if(c=='\n')        {            sort(b,b+n);//直接排下序，以后无需反复查询最大数据;            for(int i=0;i<n-1;i++)                cout<<a[i]<<' ';            cout<<a[n-1]<<endl;            for(int i=n-1;i>0;i--)                while(a[i]!=b[i])//当数据不再对应位子，按两种情况处理;                {                    if(a[0]==b[i])                    {                        exchange(a,i);                        cout<<n-i<<' ';                    }                    else                    {                        int j=0;                        while(a[j]!=b[i])                            j++;                        exchange(a,j);                        cout<<n-j<<' ';                    }                }            cout<<'0'<<'\n';            n=0;        }    }    return 0;}