UVa 10344 5: Full Array enumeration & backtracking

10344-23 out of 5

Time limit:3.000 seconds

Http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem &problem=1285

Your task is to write a program so can decide whether can find a arithmetic expression consisting of five given Num Bers (1<=i<=5) that would yield the value 23. For this problem we'll only consider arithmetic expressions of the following from:

Where: {1,2,3,4,5}-> {1,2,3,4,5} is a bijective function

and  {+,-, *} (1<=I<=4)

Input

The Input consists of 5-tupels of positive integers, each between 1 and 50. The Input is terminated by a line containing five zero ' s. This line should is processed.

Output

This article URL address: http://www.bianceng.cn/Programming/sjjg/201410/45364.htm

For each 5-tupel print "Possible" (without quotes) if their exists a arithmetic expression (as described) that above DS 23. Otherwise print "impossible".

Sample Input

1 1 1 1 1

1 2 3 4 5

2 3 5 7 11

0 0 0 0 0

Sample Output

Impossible

Possible

Possible

Water problem.

Complete code:

/*0.279s*/
    
#include <cstdio>  
#include <algorithm>  
using namespace std;  
    
int a[5];  
BOOL Flag;  
    
void Dfs (int cur, int ans)  
{  
    if (cur = 5)  
    {  
        if (ans = =) flag = true;  
        return;  
    }  
    if (!flag) DFS (cur + 1, ans + a[cur]);  
    if (!flag) DFS (cur + 1, ans-a[cur]);  
    if (!flag) DFS (cur + 1, ans * a[cur]);  
    
int main ()  
{while  
    (scanf ("%d%d%d%d%d", &a[0], &a[1], &a[2], &a[3], &a[4), a[0])  
    {  
        flag = false;  
        Sort (A, a + 5);  
        Do
        {  
            dfs (1, a[0]);  
            if (flag) break;  
        while (Next_permutation (A, A + 5));  
        Puts (flag?) "Possible": "Impossible");  
    return 0;  
}