checking out exercise alphanumeric

go/alphametics/README.md

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+# Alphametics
+
+Write a function to solve alphametics puzzles.
+
+[Alphametics](https://en.wikipedia.org/wiki/Alphametics) is a puzzle where
+letters in words are replaced with numbers.
+
+For example `SEND + MORE = MONEY`:
+
+```text
+  S E N D
+  M O R E +
+-----------
+M O N E Y
+```
+
+Replacing these with valid numbers gives:
+
+```text
+  9 5 6 7
+  1 0 8 5 +
+-----------
+1 0 6 5 2
+```
+
+This is correct because every letter is replaced by a different number and the
+words, translated into numbers, then make a valid sum.
+
+Each letter must represent a different digit, and the leading digit of
+a multi-digit number must not be zero.
+
+Write a function to solve alphametics puzzles.
+
+## Implementation
+
+Define a single Go func, Solve, which accepts a puzzle string which may have zero
+or more + operators, and one == operator; Solve should attempt to solve the alphametics puzzle
+and return a map of all the letter substitutions for both the puzzle and the addition solution.
+
+Use the following signature for func Solve:
+
+```
+func Solve(puzzle string) (map[string]int, error) {
+```
+Solve should return an error if there is no solution to the given puzzle.
+
+An example puzzle and returned solution is:
+```
+Solve("SEND + MORE == MONEY")
+```
+would return
+```
+map[string]int{"M":1, "O":0, "N":6, "E":5, "Y":2, "S":9, "D":7, "R":8}, nil
+```
+
+```text
+  S E N D
+  M O R E +
+-----------
+M O N E Y
+```
+
+Replacing these with valid numbers gives:
+
+```text
+  9 5 6 7
+  1 0 8 5 +
+-----------
+1 0 6 5 2
+```
+
+
+
+## Coding the solution
+
+Look for a stub file having the name alphametics.go
+and place your solution code in that file.
+
+## Running the tests
+
+To run the tests run the command `go test` from within the exercise directory.
+
+If the test suite contains benchmarks, you can run these with the `--bench` and `--benchmem`
+flags:
+
+    go test -v --bench . --benchmem
+
+Keep in mind that each reviewer will run benchmarks on a different machine, with
+different specs, so the results from these benchmark tests may vary.
+
+## Further information
+
+For more detailed information about the Go track, including how to get help if
+you're having trouble, please visit the exercism.io [Go language page](http://exercism.io/languages/go/resources).
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

go/alphametics/alphametics.go

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+package alphametics

go/alphametics/alphametics_test.go

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+package alphametics
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestSolve(t *testing.T) {
+	for _, tc := range testCases {
+		s, err := Solve(tc.input)
+		switch {
+		case tc.errorExpected:
+			if err == nil {
+				t.Fatalf("FAIL: %s\nSolve(%q)\nExpected error\nActual: %#v",
+					tc.description, tc.input, s)
+			}
+		case err != nil:
+			t.Fatalf("FAIL: %s\nSolve(%q)\nExpected: %#v\nGot error: %q",
+				tc.description, tc.input, tc.expected, err)
+		case !reflect.DeepEqual(s, tc.expected):
+			t.Fatalf("FAIL: %s\nSolve(%q)\nExpected: %#v\nActual: %#v",
+				tc.description, tc.input, tc.expected, s)
+		}
+		t.Logf("PASS: %s", tc.description)
+	}
+}
+
+func BenchmarkSolve(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testCases {
+			Solve(tc.input)
+		}
+	}
+}

go/alphametics/cases_test.go

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+package alphametics
+
+// Source: exercism/problem-specifications
+// Commit: 361cf3c alphametics: v1.3.0 Add test for two digits carry (#1344)
+// Problem Specifications Version: 1.3.0
+
+// Solve the alphametics puzzle
+var testCases = []struct {
+	description   string
+	input         string
+	expected      map[string]int
+	errorExpected bool
+}{
+	{
+		description: "puzzle with three letters",
+		input:       "I + BB == ILL",
+		expected:    map[string]int{"B": 9, "I": 1, "L": 0},
+	},
+	{
+		description:   "solution must have unique value for each letter",
+		input:         "A == B",
+		errorExpected: true,
+	},
+	{
+		description:   "leading zero solution is invalid",
+		input:         "ACA + DD == BD",
+		errorExpected: true,
+	},
+	{
+		description: "puzzle with two digits final carry",
+		input:       "A + A + A + A + A + A + A + A + A + A + A + B == BCC",
+		expected:    map[string]int{"A": 9, "B": 1, "C": 0},
+	},
+	{
+		description: "puzzle with four letters",
+		input:       "AS + A == MOM",
+		expected:    map[string]int{"A": 9, "M": 1, "O": 0, "S": 2},
+	},
+	{
+		description: "puzzle with six letters",
+		input:       "NO + NO + TOO == LATE",
+		expected:    map[string]int{"A": 0, "E": 2, "L": 1, "N": 7, "O": 4, "T": 9},
+	},
+	{
+		description: "puzzle with seven letters",
+		input:       "HE + SEES + THE == LIGHT",
+		expected:    map[string]int{"E": 4, "G": 2, "H": 5, "I": 0, "L": 1, "S": 9, "T": 7},
+	},
+	{
+		description: "puzzle with eight letters",
+		input:       "SEND + MORE == MONEY",
+		expected:    map[string]int{"D": 7, "E": 5, "M": 1, "N": 6, "O": 0, "R": 8, "S": 9, "Y": 2},
+	},
+	{
+		description: "puzzle with ten letters",
+		input:       "AND + A + STRONG + OFFENSE + AS + A + GOOD == DEFENSE",
+		expected:    map[string]int{"A": 5, "D": 3, "E": 4, "F": 7, "G": 8, "N": 0, "O": 2, "R": 1, "S": 6, "T": 9},
+	},
+	{
+		description: "puzzle with ten letters and 199 addends",
+		input:       "THIS + A + FIRE + THEREFORE + FOR + ALL + HISTORIES + I + TELL + A + TALE + THAT + FALSIFIES + ITS + TITLE + TIS + A + LIE + THE + TALE + OF + THE + LAST + FIRE + HORSES + LATE + AFTER + THE + FIRST + FATHERS + FORESEE + THE + HORRORS + THE + LAST + FREE + TROLL + TERRIFIES + THE + HORSES + OF + FIRE + THE + TROLL + RESTS + AT + THE + HOLE + OF + LOSSES + IT + IS + THERE + THAT + SHE + STORES + ROLES + OF + LEATHERS + AFTER + SHE + SATISFIES + HER + HATE + OFF + THOSE + FEARS + A + TASTE + RISES + AS + SHE + HEARS + THE + LEAST + FAR + HORSE + THOSE + FAST + HORSES + THAT + FIRST + HEAR + THE + TROLL + FLEE + OFF + TO + THE + FOREST + THE + HORSES + THAT + ALERTS + RAISE + THE + STARES + OF + THE + OTHERS + AS + THE + TROLL + ASSAILS + AT + THE + TOTAL + SHIFT + HER + TEETH + TEAR + HOOF + OFF + TORSO + AS + THE + LAST + HORSE + FORFEITS + ITS + LIFE + THE + FIRST + FATHERS + HEAR + OF + THE + HORRORS + THEIR + FEARS + THAT + THE + FIRES + FOR + THEIR + FEASTS + ARREST + AS + THE + FIRST + FATHERS + RESETTLE + THE + LAST + OF + THE + FIRE + HORSES + THE + LAST + TROLL + HARASSES + THE + FOREST + HEART + FREE + AT + LAST + OF + THE + LAST + TROLL + ALL + OFFER + THEIR + FIRE + HEAT + TO + THE + ASSISTERS + FAR + OFF + THE + TROLL + FASTS + ITS + LIFE + SHORTER + AS + STARS + RISE + THE + HORSES + REST + SAFE + AFTER + ALL + SHARE + HOT + FISH + AS + THEIR + AFFILIATES + TAILOR + A + ROOFS + FOR + THEIR + SAFE == FORTRESSES",
+		expected:    map[string]int{"A": 1, "E": 0, "F": 5, "H": 8, "I": 7, "L": 2, "O": 6, "R": 3, "S": 4, "T": 9},
+	},
+}

go/alphametics/go.mod

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+module alphametics
+
+go 1.13