feat: cap3 ex33 ~ ex41

cap3/ex34.go

@@ -1 +1,71 @@
 package cap3
+
+import "fmt"
+
+const (
+	_opAdd   = '+' // 加
+	_opMinus = '-' // 减
+	_opMulti = '*' // 乘
+	_opDiv   = '/' // 除
+)
+
+var allOperations = [4]byte{_opAdd, _opMinus, _opMulti, _opDiv}
+
+func Ex34(x1, x2, x3, x4, x5, y int) []string {
+	result := make([]string, 0)
+	operations := make([]byte, 4)
+	nums := [5]int{x1, x2, x3, x4, x5}
+
+	// 一层一层尝试运算符
+	for _, operations[0] = range allOperations {
+		// 当前为除法，判断下一个数是否为0，如果是则直接跳过，下同
+		if operations[0] == _opDiv && nums[1] == 0 {
+			continue
+		}
+		for _, operations[1] = range allOperations {
+			if operations[1] == _opDiv && nums[2] == 0 {
+				continue
+			}
+			for _, operations[2] = range allOperations {
+				if operations[2] == _opDiv && nums[3] == 0 {
+					continue
+				}
+				for _, operations[4] = range allOperations {
+					if operations[4] == _opDiv && nums[4] == 0 {
+						continue
+					}
+
+					// 计算表达式
+					p, f, q := 0, 1, nums[1]
+					for i, op := range operations {
+						switch op {
+						case _opAdd:
+							p += f * q
+							f, q = 1, nums[i+1]
+						case _opMinus:
+							p += f * q
+							f, q = -1, nums[i+1]
+						case _opMulti:
+							q *= nums[i+1]
+						case _opDiv:
+							q /= nums[i+1]
+						}
+					}
+
+					// 结果等于给定的数字y，添加到结果集中
+					if p+f*q == y {
+						text := ""
+						for _, num := range nums {
+							text += fmt.Sprintf("%d %c ", num, operations)
+						}
+
+						text += fmt.Sprintf("%d = %d\n", nums[4], y)
+						result = append(result, text)
+					}
+				}
+			}
+		}
+	}
+
+	return result
+}

cap3/ex35.go

@@ -1 +1,24 @@
 package cap3
+
+func Ex35(boxNum int, expectWeigh, actualWeigh int) []int {
+	result := make([]int, 0)
+
+	// 实际值重量正常重量差 / 10
+	w := (expectWeigh - actualWeigh) / 10
+	// w转化为2的幂的和
+	for w != 0 {
+		// k是箱子编号，从0开始， t是2的幂
+		k, t := 0, 1
+		// 找到最接近w的2的k次方t，当t大于w时结束小循环
+		for w-t >= 0 {
+			t *= 2
+			// t是2的k次方
+			k++
+		}
+
+		result = append(result, k-1)
+		w -= t / 2
+	}
+
+	return result
+}

cap3/ex36.go

@@ -1 +1,20 @@
 package cap3
+
+func Ex36(num int) []int {
+	// 用另外一种写法，直接存能整除的数
+	divNums := make([]int, 0)
+
+	if num%3 == 0 {
+		divNums = append(divNums, 3)
+	}
+
+	if num%5 == 0 {
+		divNums = append(divNums, 5)
+	}
+
+	if num%7 == 0 {
+		divNums = append(divNums, 7)
+	}
+
+	return divNums
+}

cap3/ex37.go

@@ -1 +1,24 @@
 package cap3
+
+func Ex37(n int) []int {
+	var coeff func(nums []int, n int)
+	coeff = func(nums []int, n int) {
+		if n <= 0 {
+			return
+		}
+
+		// 第一个和最后一个数字肯定是1
+		nums[0] = 1
+		coeff(nums, n-1)
+		nums[n] = 1
+
+		for i := n - 1; i > 0; i-- {
+			nums[i] += nums[i-1]
+		}
+	}
+
+	nums := make([]int, n+1)
+	coeff(nums, n)
+
+	return nums
+}

cap3/ex38.go

@@ -1 +1,33 @@
 package cap3
+
+func Ex38(k int, nums []int) {
+	gcd := func(m, n int) int {
+		a, b := m, n
+		if m < n {
+			a, b = n, m
+		}
+
+		r := a % b
+		for r != 0 {
+			a = b
+			b = r
+			r = a % b
+		}
+
+		return b
+	}
+
+	numsLen := len(nums)
+	first, gcdNumb := 0, gcd(numsLen, k)
+	for i := 0; i < gcdNumb; i++ {
+		first = nums[i]
+		startIdx := i
+		for j := 0; j < numsLen/gcdNumb; j++ {
+			startIdx = (startIdx + k) % numsLen
+			// 交换
+			tmp := nums[startIdx]
+			nums[startIdx] = first
+			first = tmp
+		}
+	}
+}

cap3/ex39.go

@@ -1 +1,10 @@
 package cap3
+
+func Ex39(a, b, c int) int {
+	result := 70*a + 21*b + 15*c
+	for result > 105 {
+		result -= 105
+	}
+
+	return result
+}

cap3/ex40.go

@@ -1 +1,18 @@
 package cap3
+
+func Ex40(n int) int {
+	var fab func(n int) int
+	fab = func(n int) int {
+		if n == 1 {
+			return 1
+		}
+
+		if n == 2 {
+			return 2
+		}
+
+		return fab(n-1) + fab(n-2)
+	}
+
+	return fab(n)
+}

cap3/ex41.go

@@ -1 +1,16 @@
 package cap3
+
+import "math"
+
+func Ex41(t int) (float64, float64) {
+	a, b := math.Pow(3, float64(t))/4, math.Pow(3, float64(t+1))/4
+	if t%2 == 0 {
+		a -= 0.75
+		b += 0.75
+	} else {
+		a += 0.75
+		b -= 0.75
+	}
+
+	return a, b
+}