sol 1 2 3 4 5 6 7 8 9 = 100

sol1to9.go

package main

import (
	"fmt"
)

func main() {
	sol()
}

type op struct {
	fn     func(a, b float64) (float64, bool)
	order  int
	symbol string
}

func sol() {
	opA := &op{
		fn: func(a, b float64) (float64, bool) {
			return a + b, true
		},
		order:  3,
		symbol: "+",
	}
	opS := &op{
		fn: func(a, b float64) (float64, bool) {
			return a - b, true
		},
		order:  3,
		symbol: "-",
	}
	opM := &op{
		fn: func(a, b float64) (float64, bool) {
			return a * b, true
		},
		order:  2,
		symbol: "*",
	}
	opD := &op{
		fn: func(a, b float64) (float64, bool) {
			return a / b, true
		},
		order:  2,
		symbol: "/",
	}
	opC := &op{
		fn: func(a, b float64) (float64, bool) {
			return 10*a + b, a > 0
		},
		order:  1,
		symbol: "",
	}
	opArr := []*op{opC, opM, opD, opA, opS}

	cnt := 0
	for i0 := 0; i0 < len(opArr); i0++ {
		for i1 := 0; i1 < len(opArr); i1++ {
			for i2 := 0; i2 < len(opArr); i2++ {
				for i3 := 0; i3 < len(opArr); i3++ {
					for i4 := 0; i4 < len(opArr); i4++ {
						for i5 := 0; i5 < len(opArr); i5++ {
							for i6 := 0; i6 < len(opArr); i6++ {
								for i7 := 0; i7 < len(opArr); i7++ {
									myops := []*op{opArr[i0], opArr[i1], opArr[i2], opArr[i3], opArr[i4], opArr[i5], opArr[i6], opArr[i7]}
									if b, c := calc(myops, 100); b {
										cnt++
										fmt.Printf("%d. %s\n", cnt, c)										
									}
								}
							}
						}
					}
				}
			}
		}
	}

}

func calc(myops []*op, target float64) (bool, string) {
	cnt := 0
	for _, o := range myops {
		if o.order > 1 {
			cnt++
		}
	}

	dgs := []float64{1, 2, 3, 4, 5, 6, 7, 8, 9}
	txt := "1"
	for i, o := range myops {
		txt = fmt.Sprintf("%s%s%.0f", txt, o.symbol, dgs[i+1])
	}
	for n := 1; n <= 3; n++ {
		i := 0
		for i < len(myops) {
			to := myops[i]
			if to.order == n {
				if v, b := to.fn(dgs[i], dgs[i+1]); b {
					myops = append(myops[:i], myops[i+1:]...)
					dgs[i] = v
					dgs = append(dgs[:i+1], dgs[i+2:]...)
				} else {
					return false, ""
				}
			} else {
				i++
			}
		}
	}
	if dgs[0] == target {
		return true, fmt.Sprintf("使用%d種運算子，有效結果=%s=%.0f", cnt, txt, target)
	}
	return false, ""
}

型別改成 float64 找到漏網之魚

• 1*2/3+4*5/6+7+89=100
• 1/2*34-5+6-7+89=100
• 1/2*3/4*56+7+8*9=100
• 1/2/3*456+7+8+9=10