leetcode-go/easy/13.go

package main

import (
	"strings"
    "fmt"
    "math"
)

// iterator of countAndSay function
func casIter(last string, n int) string {
    if n == 1 { return last }
    next := make([]rune, 0)
    curr := last[0]
    cnt := 1
    for i := 1; i < len(last); i++ {
        if curr != last[i] {
            next = append(next, rune(cnt + '0'), rune(curr))
            curr = last[i]
            cnt = 1
        } else {
            cnt++
        }
    }
    next = append(next, rune(cnt + '0'), rune(curr))    
    return casIter(string(next), n - 1)
}

func countAndSay(n int) string {
    return casIter("1", n)
}