Exemple #1
0
func problem62() *big.Int {
	cubes := make(map[string]*entry)
	one, three := big.NewInt(1), big.NewInt(3)

	for i := big.NewInt(0); ; i.Add(i, one) {
		x := new(big.Int).Exp(i, three, nil) // x := i**3

		// Sort the digits to produce a 'canonical' representation.
		key := tools.SortedString(x.String())
		e, ok := cubes[key]
		if !ok {
			cubes[key] = &entry{1, x}
		} else {
			e.count++
			if x.Cmp(e.min) == -1 { // x < e.min
				e.min = x
			}
			if e.count == 5 {
				return e.min
			}
		}
	}
}
Exemple #2
0
// sameDigits checks whether two ints contain the same digits.
func sameDigits(x, y int) bool {
	a := tools.SortedString(strconv.Itoa(x))
	b := tools.SortedString(strconv.Itoa(y))
	return a == b
}
Exemple #3
0
func isPerm(x, y int) bool {
	a := strconv.Itoa(x)
	b := strconv.Itoa(y)
	return tools.SortedString(a) == tools.SortedString(b)
}