POJ - 3187 Backward Digit Sums(水+全排暴搜)

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Backward Digit Sums Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 7311   Accepted: 4221 Description FJ and his cows enjoy playing a mental game. They write down the numbers from 1 to N (1 <= N <= 10) in a certain order and then sum adjacent numbers to produce a new list with one fewer number. They repeat this until only a single number is left. For example, one instance of the game (when N=4) might go like this:  3 1 2 4 4 3 6 7 9 16 Behind FJ's back, the cows have started playing a more difficult game, in which they try to determine the starting sequence from only the final total and the number N. Unfortunately, the game is a bit above FJ's mental arithmetic capabilities.  Write a program to help FJ play the game and keep up with the cows. Input Line 1: Two space-separated integers: N and the final sum. Output Line 1: An ordering of the integers 1..N that leads to the given sum. If there are multiple solutions, choose the one that is lexicographically least, i.e., that puts smaller numbers first. Sample Input 4 16 Sample Output 3 1 2 4 Hint Explanation of the sample:  There are other possible sequences, such as 3 2 1 4, but 3 1 2 4 is the lexicographically smallest. Source USACO 2006 February Gold & Silver

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给出第一行数的个数n，然后是第n行的数sum，输出第一行的排列。

思路，枚举1到n的全排列，直到找到一组数成立。

附上AC代码：

#include

using namespace std;
int a[15],s[15];
int n,N,sum;

int main()
{
    cin>>n>>sum;
   
    for(int i=1;i<=n;i++)
       a[i]=i;
    do
    {
         for(int i=1;i<=n;i++)
            s[i]=a[i];
        for(int i=n;i>1;i--)
        for(int j=1;j