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50 lines
920 B
50 lines
920 B
package choose
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import "testing"
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func didPanic(f func()) (ret bool) {
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defer func() {
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if r := recover(); r != nil {
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ret = true
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}
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}()
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f()
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return
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}
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func TestChoose(t *testing.T) {
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// Let's use Pascal's triangle for the values.
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row := append([]int64(nil), 1)
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for n := int64(0); n < 62; n++ {
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for k, v := range row {
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if x := Choose(n, int64(k)); x != v {
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t.Fatalf("%v choose %v returned %v, not %v", n, k, x, v)
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}
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}
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newRow := make([]int64, len(row)+1)
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newRow[0] = 1
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for i := 1; i < len(row); i++ {
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newRow[i] = row[i-1] + row[i]
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}
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newRow[len(row)] = 1
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row = newRow
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}
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// Ensure it panics when it should.
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if !didPanic(func() {
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Choose(3, 4)
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}) {
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t.Fatal("Choose did not panic when k > n.")
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}
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if !didPanic(func() {
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Choose(3, -1)
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}) {
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t.Fatal("Choose did not panic when k < 0")
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}
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}
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func BenchmarkChoose(b *testing.B) {
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for i := 0; i < b.N; i++ {
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Choose(61, 30)
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}
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}
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