func Problem_27() int {
cache := make(map[uint64][]uint64)
maxCount, maxA, maxB := 0, 0, 0
for a := -999; a < 1000; a++ {
for b := -999; b < 1000; b++ {
primeCount := 0
var prime bool
for n := 0; ; n++ {
test := uint64(math.Abs(float64(int(math.Pow(float64(n), 2)) + a*n + b)))
if cache, prime = helpers.IsPrime(test, cache); prime {
primeCount++
} else {
break
}
}
if primeCount > maxCount {
maxCount, maxA, maxB = primeCount, a, b
}
}
}
product := maxA * maxB
fmt.Printf("The coefficients a=%d and b=%d with product %d produce %d "+
"primes\n", maxA, maxB, product, maxCount)
return product
}
func Problem_35() int {
count := 0
cache := make(map[uint64][]uint64)
for i := 2; i < 1000000; i++ {
var result bool
circular := true
for _, rotation := range helpers.Rotations(i) {
if cache, result = helpers.IsPrime(uint64(rotation), cache); !result {
circular = false
}
}
if circular {
count += 1
}
}
fmt.Printf("There are %d circular primes below 1,000,000\n", count)
return count
}
func Problem_7() uint64 {
var i uint64 = 0
var count int = 0
cache := make(map[uint64][]uint64)
fmt.Println("Calculating the 10,001st prime number")
for {
var result bool
if cache, result = helpers.IsPrime(i, cache); result {
count++
if count == 10001 {
fmt.Printf("The 10,001st prime number is %d\n", i)
break
}
}
i++
}
return i
}
func Problem_10() uint64 {
fmt.Print("Finding sum of all primes < 2,000,000")
var i uint64
var result bool
var sum uint64 = 0
cache := make(map[uint64][]uint64)
for i = 0; i < 2000000; i++ {
if cache, result = helpers.IsPrime(i, cache); result {
sum += i
}
// Display progress dots
if i%250000 == 0 {
fmt.Print(".")
}
}
fmt.Printf("\nSum is %d\n", sum)
return sum
}