ArithmeticEquation | Topcoder Archive

Problem Statement

You are given a String s that consists of only digits. You would like to transform it into a correct arithmetic equality of the form "X+Y=Z", "X-Y=Z" or "X*Y=Z" (quotes for clarity), where X, Y and Z are integers with no extra leading zeroes. To do this, you are allowed to replace one character in s with '+', '-' or '*', and another with '=' (the '=' character must appear later than the operator).

Return the equality into which s can be transformed. If there are multiple possibilities, return the one that comes first lexicographically. If there is no solution, return "NO SOLUTION" (quotes for clarity).

Definition

Class:: ArithmeticEquation
Method:: createEquality
Parameters:: String
Returns:: String
Method signature:: String createEquality(String s)
(be sure your method is public)

Notes

The lexicographical ordering for characters in this problem is: '*', '+', '-', '0', ..., '9', '='.

Constraints

s will contain only digits ('0'-'9').
s will contain between 5 and 10 characters, inclusive.

Examples

```
"22224"
```
```
Returns: "2*2=4"
```
There are two solutions in this case: "2+2=4" and "2*2=4". The one with multiplication comes first lexicographically.
```
"22223"
```
```
Returns: "NO SOLUTION"
```
```
"22220"
```
```
Returns: "2-2=0"
```
Extra leading zeroes are forbidden, but 0 by itself is allowed.
```
"1111111122"
```
```
Returns: "11+111=122"
```
```
"000000"
```
```
Returns: "NO SOLUTION"
```

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