Initial Commit

go/largest-series-product/README.md

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+# Largest Series Product
+
+Write a program that, when given a string of digits, can calculate the largest product for a series of consecutive digits of length n.
+
+For example, for the input `'0123456789'`, the largest product for a
+series of 3 digits is 504 (7 * 8 * 9), and the largest product for a
+series of 5 digits is 15120 (5 * 6 * 7 * 8 * 9).
+
+For the input `'73167176531330624919225119674426574742355349194934'`,
+the largest product for a series of 6 digits is 23520.
+
+To run the tests simply run the command `go test` in the exercise directory.
+
+If the test suite contains benchmarks, you can run these with the `-bench`
+flag:
+
+    go test -bench .
+
+For more detailed info about the Go track see the [help
+page](http://help.exercism.io/getting-started-with-go.html).
+
+## Source
+
+A variation on Problem 8 at Project Euler [view source](http://projecteuler.net/problem=8)

go/largest-series-product/cases_test.go

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+package lsproduct
+
+// Source: exercism/x-common
+// Commit: 3764abd Merge pull request #167 from petertseng/largest-series-product-json
+
+var tests = []struct {
+	digits  string
+	span    int
+	product int64
+	ok      bool
+}{
+	{"0123456789", 2, 72, true},
+	{"576802143", 2, 48, true},
+	{"29", 2, 18, true},
+	{"0123456789", 3, 504, true},
+	{"1027839564", 3, 270, true},
+	{"0123456789", 5, 15120, true},
+	{"73167176531330624919225119674426574742355349194934", 6, 23520, true},
+	{"52677741234314237566414902593461595376319419139427", 6, 28350, true},
+	{"7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450", 13, 23514624000, true},
+	{"0000", 2, 0, true},
+	{"99099", 3, 0, true},
+	{"123", 4, -1, false},
+	{"", 0, 1, true},
+	{"123", 0, 1, true},
+	{"", 1, -1, false},
+	{"1234a5", 2, -1, false},
+	{"12345", -1, -1, false},
+}

go/largest-series-product/largest_series_product.go

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+package lsproduct
+
+import "fmt"
+
+// TestVersion defines version testing.
+const TestVersion = 1
+
+// LargestSeriesProduct Takes an input string of digits
+// and a length for the series. It returns the largest
+// series product from that string of that length.
+func LargestSeriesProduct(input string, size int) (int, error) {
+	if size == 0 {
+		return 1, nil
+	} else if size > len(input) {
+		return 0, fmt.Errorf("Invalid Span Size")
+	}
+	var high int
+	for i := 0; i < (len(input) - size + 1); i++ {
+		try := GetProduct(input[i : i+size])
+		if try < 0 {
+			return 0, fmt.Errorf("Invalid input")
+		}
+		if try > high {
+			high = try
+		}
+	}
+	return high, nil
+}
+
+// GetProduct takes a string of numbers, splits it up
+// and returns the product of them
+func GetProduct(input string) int {
+	if len(input) > 0 {
+		total := 1
+		for i := range input {
+			next := input[i] - 48
+			if next < 0 || next > 9 {
+				return -1
+			}
+			total = total * int(next)
+		}
+		return total
+	}
+	return 0
+}

go/largest-series-product/largest_series_product_test.go

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+package lsproduct
+
+import "testing"
+
+const testVersion = 1
+
+// Retired testVersions
+// (none) ba7a22a355a32901caf46529c799fa53118ded0a
+
+var tests = []struct {
+	digits  string
+	span    int
+	product int64
+	ok      bool
+}{
+	{"0123456789",
+		2, 72, true},
+	{"12",
+		2, 2, true},
+	{"19",
+		2, 9, true},
+	{"576802143",
+		2, 48, true},
+	{"0123456789",
+		3, 504, true},
+	{"1027839564",
+		3, 270, true},
+	{"0123456789",
+		5, 15120, true},
+	{"73167176531330624919225119674426574742355349194934",
+		6, 23520, true},
+	{"52677741234314237566414902593461595376319419139427",
+		6, 28350, true},
+	{"",
+		0, 1, true},
+	{"123",
+		4, 0, false},
+	{pe1k, 5, 40824, true},        // original PE problem
+	{pe1k, 13, 23514624000, true}, // new PE problem
+}
+
+const pe1k = "73167176531330624919225119674426574742355349194934" +
+	"96983520312774506326239578318016984801869478851843" +
+	"85861560789112949495459501737958331952853208805511" +
+	"12540698747158523863050715693290963295227443043557" +
+	"66896648950445244523161731856403098711121722383113" +
+	"62229893423380308135336276614282806444486645238749" +
+	"30358907296290491560440772390713810515859307960866" +
+	"70172427121883998797908792274921901699720888093776" +
+	"65727333001053367881220235421809751254540594752243" +
+	"52584907711670556013604839586446706324415722155397" +
+	"53697817977846174064955149290862569321978468622482" +
+	"83972241375657056057490261407972968652414535100474" +
+	"82166370484403199890008895243450658541227588666881" +
+	"16427171479924442928230863465674813919123162824586" +
+	"17866458359124566529476545682848912883142607690042" +
+	"24219022671055626321111109370544217506941658960408" +
+	"07198403850962455444362981230987879927244284909188" +
+	"84580156166097919133875499200524063689912560717606" +
+	"05886116467109405077541002256983155200055935729725" +
+	"71636269561882670428252483600823257530420752963450"
+
+func TestLargestSeriesProduct(t *testing.T) {
+	if TestVersion != testVersion {
+		t.Fatalf("Found TestVersion = %v, want %v", TestVersion, testVersion)
+	}
+	for _, test := range tests {
+		p, err := LargestSeriesProduct(test.digits, test.span)
+		switch {
+		case err != nil:
+			if test.ok {
+				t.Fatalf("LargestSeriesProduct(%s, %d) returned error %q.  "+
+					"Error not expected.",
+					test.digits, test.span, err)
+			}
+		case !test.ok:
+			t.Fatalf("LargestSeriesProduct(%s, %d) = %d, %v.  Expected error",
+				test.digits, test.span, p, err)
+		case int64(p) != test.product:
+			t.Fatalf("LargestSeriesProduct(%s, %d) = %d, want %d",
+				test.digits, test.span, p, test.product)
+		}
+	}
+}
+
+func BenchmarkLargestSeriesProduct(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, test := range tests {
+			LargestSeriesProduct(test.digits, test.span)
+		}
+	}
+}