05-01_counting_ones_test.go

package hd_test

import (
	"fmt"
	"testing"

	hd "github.com/nikolaydubina/go-hackers-delight"
)

func ExampleCountOnes() {
	fmt.Println(hd.CountOnes5(uint32(0b0000_0100_0100_01110)))
	// Output: 5
}

func FuzzCountOnes(f *testing.F) {
	for _, x := range fuzzUint32 {
		f.Add(x)
	}

	f.Fuzz(func(t *testing.T, x uint32) {
		// definition
		var n uint32 = 0
		for i := range 32 {
			if (x & (1 << i)) != 0 {
				n++
			}
		}

		vs := []uint32{
			hd.CountOnes(x),
			hd.CountOnes1(x),
			//hd.CountOnes2(x),
			hd.CountOnes3(x),
			hd.CountOnes4(x),
		}
		if x <= ((1 << 15) - 1) {
			vs = append(vs, hd.CountOnes5(x))
		}

		for i, v := range vs {
			if v != n {
				t.Error(i, "x", fmt.Sprintf("%032b", x), "exp", n, "got", v)
			}
		}
	})
}

func ExampleCompareCountOnes_same() {
	var x uint32 = 0b0000_0100_0100_01110
	var y uint32 = 0b0000_0100_0100_01110
	fmt.Println(hd.CompareCountOnes(x, y))
	// Output: 0
}

func ExampleCompareCountOnes_left_smaller() {
	var x uint32 = 0b0000_0100_0100_01110
	var y uint32 = 0b0000_0100_0100_01111
	fmt.Println(hd.CompareCountOnes(x, y))
	// Output: -1
}

func ExampleCompareCountOnes_left_bigger() {
	var x uint32 = 0b0000_0100_0100_01111
	var y uint32 = 0b0000_0100_0100_01110
	fmt.Println(hd.CompareCountOnes(x, y))
	// Output: 1
}

func FuzzCompareCountOnes(f *testing.F) {
	for _, x := range fuzzUint32 {
		for _, y := range fuzzUint32 {
			f.Add(x, y)
		}
	}

	f.Fuzz(func(t *testing.T, x, y uint32) {
		// definition
		var nx, ny uint32 = 0, 0
		for i := range 32 {
			if (x & (1 << i)) != 0 {
				nx++
			}
			if (y & (1 << i)) != 0 {
				ny++
			}
		}

		switch v := hd.CompareCountOnes(x, y); v {
		case 1:
			if nx < ny {
				t.Errorf("< %v %032b %032b", v, x, y)
			}
		case 0:
			if nx != ny {
				t.Errorf("= %v %032b %032b", v, x, y)
			}
		case -1:
			if nx > ny {
				t.Errorf("> %v %032b %032b", v, x, y)
			}
		}
	})
}

func ExampleCountOnesArrayGroup8() {
	vs := []uint32{
		0b0000_0100_0100_01110,
		0b0001_0100_0100_01110,
		0b0000_0100_0100_01110,
		0b0011_0100_0100_01110,
		0b0000_0100_0100_01110,
		0b0111_0100_0100_01110,
		0b1001_0100_0100_01110,
		0b0000_0100_0100_01110,
		0b0101_0100_0100_01110,
		0b0101_0100_0100_01110,
	}
	fmt.Println(hd.CountOnesArrayGroup8(vs))
	// Output: 62
}