euler53.go

package main

import (
	"fmt"
	"math/big"
	"time"
)

func makeNCRS(ncrs chan *big.Int, maxn int64) {
	var n, r int64
	var ncr, bigR *big.Int
	for n = 1; n <= maxn; n++ {
		ncr = big.NewInt(n)
		for r = 2; r <= n; r++ {
			bigR = big.NewInt(r)
			ncr = ncr.Div(ncr, bigR)
			ncr = ncr.Mul(ncr, big.NewInt(n-r+1))
			ncrs <- ncr
		}
	}
	close(ncrs)
}

func main() {
	start := time.Now()
	result := 0
	ncrs := make(chan *big.Int)
	go makeNCRS(ncrs, 100)
	max := big.NewInt(1000000)
	for ncr := range ncrs {
		if ncr.Cmp(max) > 0 {
			result += 1
		}

	}
	fmt.Println(result)
	elapsed := time.Since(start)
	fmt.Println(elapsed.Nanoseconds())
}