Added more methods to the ints package.

- Added some statistical (related to summing and countings digits) and math methods (related to powers and square roots).

ints/math.go

@@ -1,5 +1,7 @@
 package ints
 
+import "math"
+
 // Abs returns the absolute value of i.
 func Abs(i int) int {
 	if 0 > i {
@@ -69,3 +71,45 @@ func SubAbs(a, b int) int {
 	}
 	return b - a
 }
+
+// Pow returns the power of base b to the exponent e.
+func Pow(b, e int) int {
+	if 0 == e {
+		return 1
+	}
+	if 1 == e {
+		return b
+	}
+	p := b
+	for e > 1 {
+		p *= b
+		e--
+	}
+	return p
+}
+
+// Pow64 returns the power of base b to the exponent e.
+func Pow64(b, e int64) int64 {
+	if 0 == e {
+		return 1
+	}
+	if 1 == e {
+		return b
+	}
+	p := b
+	for e > 1 {
+		p *= b
+		e--
+	}
+	return p
+}
+
+// Sqrt returns square root of n.
+func Sqrt(n int) int {
+	return int(math.Sqrt(float64(n)))
+}
+
+// Sqrt64 returns square root of n.
+func Sqrt64(n int64) int64 {
+	return int64(math.Sqrt(float64(n)))
+}

ints/statistics.go

@@ -1,5 +1,33 @@
 package ints
 
+import "strconv"
+
+// Digit returns the n'th digit of i
+func Digit(n int, i uint) int {
+	return int(Digit64(int64(n), i))
+}
+
+// Digit64 returns the n'th digit of i
+func Digit64(n int64, i uint) int64 {
+	for i >= 9 {
+		n /= 1000000000
+		i -= 9
+	}
+	for i >= 6 {
+		n /= 1000000
+		i -= 6
+	}
+	for i >= 3 {
+		n /= 1000
+		i -= 3
+	}
+	for i > 0 {
+		n /= 10
+		i--
+	}
+	return n % 10
+}
+
 // Faculty returns the faculty of i.
 func Faculty(i int) int {
 	if i < 2 {
@@ -16,6 +44,24 @@ func Faculty64(i int64) int64 {
 	return i * Faculty64(i-1)
 }
 
+// IsPalindromic returns if the integer n is palindromic (reads the same backwards).
+func IsPalindromic(n int) bool {
+	if n < 10 {
+		return true
+	}
+	if n%10 == 0 {
+		return false
+	}
+	s := strconv.Itoa(n)
+	max := (len(s) + 1) / 2
+	for i := 0; i < max; i++ {
+		if s[i] != s[len(s)-i-1] {
+			return false
+		}
+	}
+	return true
+}
+
 // Permutations returns all possible permutations of the the set integers.
 func Permutations(set []int) [][]int {
 	var n = len(set)
@@ -45,3 +91,23 @@ func Permutations(set []int) [][]int {
 	}
 	return res
 }
+
+// SumDigits returns the sum of the digits of n.
+func SumDigits(n int) int {
+	var sum int
+	for n > 0 {
+		sum += n % 10
+		n /= 10
+	}
+	return int(sum)
+}
+
+// SumDigits64 returns the sum of the digits of n.
+func SumDigits64(n int64) int {
+	var sum int64
+	for n > 0 {
+		sum += n % 10
+		n /= 10
+	}
+	return int(sum)
+}