tasks a-s

Task/Number-names/Go/number-names.go

@@ -0,0 +1,54 @@
+package main
+
+import "fmt"
+
+func main() {
+    for _, n := range []int64{12, 1048576, 9e18} {
+        fmt.Println(say(n))
+    }
+}
+
+var small = []string{"", "one", "two", "three", "four", "five", "six",
+    "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen",
+    "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"}
+var tens = []string{"ones", "ten", "twenty", "thirty", "forty",
+    "fifty", "sixty", "seventy", "eighty", "ninety"}
+var illions = []string{"thousand", "million", "billion",
+    "trillion", "quadrillion", "quintillion"}
+
+func say(n int64) string {
+    switch {
+    case n < 1:
+    case n < 20:
+        return small[n]
+    case n < 100:
+        t := tens[n/10]
+        s := n % 10
+        if s > 0 {
+            t += " " + small[s]
+        }
+        return t
+    case n < 1000:
+        h := small[n/100] + " hundred"
+        s := n % 100
+        if s > 0 {
+            h += " " + say(s)
+        }
+        return h
+    default:
+        sx := say(n % 1000)
+        for i := 0; n >= 1000; i++ {
+            n /= 1000
+            p := n % 1000
+            if p > 0 {
+                ix := say(p) + " " + illions[i]
+                if sx > "" {
+                    ix += " " + sx
+                }
+                sx = ix
+            }
+        }
+        return sx
+    }
+    return ""
+}