2469: Little Y's Puzzle 1---swust Information Institute OJ

Title Description: http://www.oj.swust.edu.cn/problem/show/2469

Description

Recently, little Y has been fascinated by mathematics and is always thinking about various mathematical problems. One day, he accidentally spilled ink on the draft paper. What he can see now is "2?3?1?4" (? Indicates a place to see). Small Y's memory is good, he knows: 1, each? Only one of the three symbols is "+", "-", "=". 2. There is a total of only one "=". 3, the original formula must be an equation. Like "2+3-1=4" now he suddenly wondered how many possibilities there were to meet the above 3 requirements.

Input

multiple sets of inputs. The first row of each group has a number n. Represents a small y from left to right and can see n numbers altogether. (2<=n<=15) The second row of each group has n digits. Indicate what these n numbers are. Ensure that each number is a non-negative integer and less than 10^7.

Output

For each group, the output line, which has only one number, indicates how many possibilities satisfy the test instructions.

• Sample Input
• Raw

42 3 1 441 1 1 1

• Sample Output
• Raw

26

Hint

There must be only one symbol between the numbers, and there is no sign in front of the first number.

AC Code:

1#include <stdio.h>2 3 inta[ -];4 Chars[ -];5 intN;6 intFlag;7 intans;8 9 voidDFS (intLevel//possibility of Dfs search +-= appearingTen { One  A     if(level==n-1) -     { -         intI=0, l=a[0],r=0; the  -          while(s[i]!='='&&i<n-1) { -  -             if(s[i]=='+') l+=a[i+1]; +             Else if(s[i]=='-') l-=a[i+1]; -  +i++; A  at         } -  -          while(i<n-1) { -  -             if(s[i]=='+') r+=a[i+1]; -             Else if(s[i]=='-') r-=a[i+1]; in             Elser=a[i+1]; -  toi++; +          -         } the  *         if(L==r&&flag) ans++; $ Panax Notoginseng         return; -  the     } +  As[level]='+'; theDFS (level+1); +  -s[level]='-'; $DFS (level+1); $  -     if(flag)return; -  thes[level]='='; -flag=1;WuyiDFS (level+1); theflag=0; -  Wu } -  About intMain () $ { -      -      while(SCANF ("%d", &n)! =EOF) -     { A  +         inti; the  -ans=0; $  the          for(i=0; i<n;i++) scanf ("%d",&a[i]); the  theDFS (0); the  -printf"%d\n", ans); in  the     } the  About     return 0; the  the}

2469: Little Y's Puzzle 1---swust Information Institute OJ