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authorDimitri Sokolyuk <demon@dim13.org>2016-08-27 23:12:22 +0200
committerDimitri Sokolyuk <demon@dim13.org>2016-08-27 23:12:22 +0200
commit4f1bb81b4401686fa8860756a68c81a7b292008a (patch)
treee087c622fecb4db25ed3b5fd3df08bdce3877305
parent3ea8f591f0e15f46dd8eb196f7dae2dd6ae4116d (diff)
Solve largest
-rw-r--r--go/largest-series-product/README.md31
-rw-r--r--go/largest-series-product/cases_test.go29
-rw-r--r--go/largest-series-product/largest_series_product.go55
-rw-r--r--go/largest-series-product/largest_series_product_test.go36
-rw-r--r--go/largest-series-product/x19
5 files changed, 170 insertions, 0 deletions
diff --git a/go/largest-series-product/README.md b/go/largest-series-product/README.md
new file mode 100644
index 0000000..d9ea9be
--- /dev/null
+++ b/go/largest-series-product/README.md
@@ -0,0 +1,31 @@
+# Largest Series Product
+
+Write a program that, when given a string of digits, can calculate the largest product for a contiguous substring of digits of length n.
+
+For example, for the input `'1027839564'`, the largest product for a
+series of 3 digits is 270 (9 * 5 * 6), and the largest product for a
+series of 5 digits is 7560 (7 * 8 * 3 * 9 * 5).
+
+Note that these series are only required to occupy *adjacent positions*
+in the input; the digits need not be *numerically consecutive*.
+
+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://exercism.io/languages/go).
+
+## Source
+
+A variation on Problem 8 at Project Euler [http://projecteuler.net/problem=8](http://projecteuler.net/problem=8)
+
+## Submitting Incomplete Problems
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
diff --git a/go/largest-series-product/cases_test.go b/go/largest-series-product/cases_test.go
new file mode 100644
index 0000000..ad71012
--- /dev/null
+++ b/go/largest-series-product/cases_test.go
@@ -0,0 +1,29 @@
+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},
+}
diff --git a/go/largest-series-product/largest_series_product.go b/go/largest-series-product/largest_series_product.go
new file mode 100644
index 0000000..df7110d
--- /dev/null
+++ b/go/largest-series-product/largest_series_product.go
@@ -0,0 +1,55 @@
+package lsproduct
+
+import "errors"
+
+const testVersion = 3
+
+func check(s string) bool {
+ for _, v := range s {
+ if v < '0' || v > '9' {
+ return false
+ }
+ }
+ return true
+}
+
+func split(s string, n int) <-chan string {
+ c := make(chan string)
+ go func() {
+ for i := 0; i <= len(s)-n; i++ {
+ c <- s[i : i+n]
+ }
+ close(c)
+ }()
+ return c
+}
+
+func max(c <-chan string) int {
+ prod := func(s string) int {
+ p := 1
+ for _, v := range s {
+ p *= int(v - '0')
+ }
+ return p
+ }
+ var m int
+ for v := range c {
+ if p := prod(v); p > m {
+ m = p
+ }
+ }
+ return m
+}
+
+func LargestSeriesProduct(s string, n int) (int, error) {
+ if ok := check(s); !ok {
+ return 0, errors.New("invalid chars")
+ }
+ if n < 0 || n > len(s) {
+ return 0, errors.New("invalid length")
+ }
+ if n == 0 {
+ return 1, nil
+ }
+ return max(split(s, n)), nil
+}
diff --git a/go/largest-series-product/largest_series_product_test.go b/go/largest-series-product/largest_series_product_test.go
new file mode 100644
index 0000000..275c0a8
--- /dev/null
+++ b/go/largest-series-product/largest_series_product_test.go
@@ -0,0 +1,36 @@
+package lsproduct
+
+import "testing"
+
+const targetTestVersion = 3
+
+func TestLargestSeriesProduct(t *testing.T) {
+ if testVersion != targetTestVersion {
+ t.Fatalf("Found testVersion = %v, want %v", testVersion, targetTestVersion)
+ }
+ 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)
+ }
+ }
+}
diff --git a/go/largest-series-product/x b/go/largest-series-product/x
new file mode 100644
index 0000000..ef92038
--- /dev/null
+++ b/go/largest-series-product/x
@@ -0,0 +1,19 @@
+1234567890
+
+123
+ 234
+ 345
+ 456
+ 567
+ 678
+ 789
+ 890
+
+10 - 3 + 1
+
+12345
+ 23456
+ 34567
+ 45678
+ 56789
+ 67890