# The subject is poisonous but Codewars OJ System (II)

Source: Internet
Author: User
Kata

<4kyu>guess the Digits and Expression
Description:
Give you a multiplication arithmetic expression:

```ABC
*   CBA
-------
= 39483
```

Each character represents a diffrent digit (1-9), and your need to find the arithmetic expression This: "123 * 321 = 39483" Solutions

This is my solution:

```function Guessexpression (exp) {Let expression = ' Const REG =/\s* (\w+) \n\*\s* (\w+) \n.*\n[\d]* (\d+)/g const UNITARR = REG.EXEC (exp). Slice (1) const [Adigit, Bdigit] = Unitarr Const ADIGITLAST = adigit[adigit.length-1] Const BDIGIT  Last = bdigit[bdigit.length-1] Const DIGITLIST = [... new Set (adigit)] Const Numresult = parseint (unitarr[2)) const isodd = numresult% 2 = 1 function Veach (strs, stat = {}) {const FIRSTSTR = Strs[0] for (Let I of [1, 2, 3, 4, 5, 6, 7, 8, 9]) {if (expression) return stat[firststr] = i if (strs.length > 1) {Veach (s) Trs.slice (1), stat)} else {const REALADIGIT = [].map.call (adigit, v => stat[v]). Join (") const Realbdigit = [].map.call (bdigit, v => stat[v]). Join (') if (realadigit[0] && realbdigit[0] && (
~~realadigit * ~~realbdigit = = Numresult)) {expression = ' \${realadigit} * \${realbdigit} = \${numresult} ' if (realadigit.spliT ("). Reverse (). Join (") = = Realbdigit) {Const MIN = math.min (~~realadigit, ~~realbdigit) const
max = Math.max (~~realadigit, ~~realbdigit) expression = ' \${min} * \${max} = \${numresult} '}} }} Veach (Digitlist.join (')) return expression}```

Filing times Error: Execution Time out 12000ms
It was later thought that if the product is odd, then the two multipliers are odd, and if the product is even, then the two multipliers must have an even number
So there are the following optimizations:

```......
Const FIRSTSTR = strs[0] let
maparr = []
if (isodd) {
if (firststr = = Adigitlast | | firststr = = bdigitlast) {
Maparr = [1, 3, 5, 7, 9]
} else {
Maparr = [1, 2, 3, 4, 5, 6, 7, 8, 9]
}}
else {
if (firststr = = = Adigitlast | | Firststr = = bdigitlast) {
if (adigitlast% 2 = 1 && firststr!== adigitlast) {
Maparr = [2, 4, 6, 8]< c12/>} else if (bdigitlast% 2 = 1 && firststr!== bdigitlast) {
Maparr = [2, 4, 6, 8]
} else {
m Aparr = [1, 2, 3, 4, 5, 6, 7, 8, 9]
}}
else {
Maparr = [1, 2, 3, 4
, 5, 6, 7, 8, 9]}} for (Let I of Maparr) {
if (expression) return
...```

However, there is no egg to use, the execution time is almost the same as the previous algorithm.
So, search for relevant answers on the web and find a solution for a big guy:

```function Guessexpression (exp) {let
m = Exp.match ([\w\d]+)/g);
Let sym = [m[0], m[1]];
Let res = +m[2];

Let Uniq = (Sym[0] + sym[1]). Split (")
. Filter (EL, I, arr) => Arr.indexof (el, i+1) = = 1);

Let nums = new Array (uniq.length). Fill (1);

Brute Force
while (1) {let
a = Sym[0].replace (/./g, C => Nums[uniq.indexof (c)]);
Let B = Sym[1].replace (/./g, C => Nums[uniq.indexof (c)]);
if ((+a) * (+b) = = Res) {return
' \${a} * \${b} = \${res} ';
}
for (Let i = 0; i < nums. length; ++i) {
Nums[i] + = 1;
if (Nums[i] >=) {
nums[i] = 1;
} else {break
;
}

}}}```

Using the Console.time test, the big guy's solution is almost half my solution.
Frustrating is: Codewars OJ with the solution of the big guy did not pass the test, I do not know how to optimize my solution. RELATED LINKS Train:guess the Digits and Expression | The solution to codewars Big Brother

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