Merge pull request #585 from 0xff-dev/241

Add solution and test-cases for problem 241

leetcode/201-300/0241.Different-Ways-to-Add-Parentheses/Solution.go

@@ -53,3 +53,96 @@ func ways(input string, cache map[string][]int) []int {
 
 	return ans
 }
+
+// Solution2
+type operation struct {
+	val int
+	op  byte
+}
+
+func calResult(a, b int, op byte) int {
+	if op == '*' {
+		return a * b
+	}
+	if op == '+' {
+		return a + b
+	}
+	return a - b
+}
+
+func diffWaysToCompute2(expression string) []int {
+	opts := make([]operation, 0)
+	base := 1
+	c := 0
+	// 245
+	for idx := len(expression) - 1; idx >= 0; idx-- {
+		if expression[idx] >= '0' && expression[idx] <= '9' {
+			c = base*int(expression[idx]-'0') + c
+			base *= 10
+			continue
+		}
+		opts = append(opts, operation{val: c}, operation{op: expression[idx]})
+		base, c = 1, 0
+	}
+	opts = append(opts, operation{val: c})
+
+	length := len(opts)
+	if length == 1 {
+		return []int{opts[0].val}
+	}
+	for s, e := 0, length-1; s < e; s, e = s+1, e-1 {
+		opts[s], opts[e] = opts[e], opts[s]
+	}
+
+	ans := make([]int, 0)
+	dp := make([][]map[int]int, length)
+	// 需要明确dp[i][j] 能计算出多少种结果
+	for i := 0; i < length; i++ {
+		dp[i] = make([]map[int]int, length)
+		for j := 0; j < length; j++ {
+			dp[i][j] = make(map[int]int)
+		}
+		if i&1 == 0 {
+			dp[i][i][opts[i].val] = 1
+		}
+	}
+
+	// 2 - 1 - 1-1
+	// n=2 0-2, 2-4, 4-6
+	// n=3,0-4, 2-6
+	// n=4,0-6
+	// n = 4 end=6
+	// length=7
+	// 2-1
+	// 2 有一个操作数，3有两个，4有3个
+	// 2 = 1+0
+	// 3 = 2+1
+	// 4 = 3 + 2
+	// length - 1 - n+1 -n+2
+
+	for n := 2; n <= length/2+1; n++ {
+		for start := 0; start < length+2-2*n; start += 2 {
+			end := start + 2*(n-1)
+			for k := start; k < end; k += 2 {
+				for v1, c1 := range dp[start][k] {
+					for v2, c2 := range dp[k+2][end] {
+						r := calResult(v1, v2, opts[k+1].op)
+						dp[start][end][r] += c1 * c2
+					}
+				}
+			}
+		}
+	}
+	for idx := length - 1; idx > 0; idx -= 2 {
+		op := opts[idx-1].op
+		for v1, c1 := range dp[idx][length-1] {
+			for v2, c2 := range dp[0][idx-2] {
+				r := calResult(v2, v1, op)
+				for loop := c1 * c2; loop > 0; loop-- {
+					ans = append(ans, r)
+				}
+			}
+		}
+	}
+	return ans
+}

leetcode/201-300/0241.Different-Ways-to-Add-Parentheses/Solution_test.go

@@ -1,6 +1,7 @@
 package Solution
 
 import (
+	"sort"
 	"strconv"
 	"testing"
 )
@@ -12,8 +13,9 @@ func TestSolution(t *testing.T) {
 		inputs string
 		expect []int
 	}{
-		{"TestCase", "2-1-1", []int{0, 2}},
-		{"TestCase", "2*3-4*5", []int{-34, -14, -10, -10, 10}},
+		{"TestCase1", "2-1-1", []int{0, 2}},
+		{"TestCase2", "2*3-4*5", []int{-34, -14, -10, -10, 10}},
+		{"TestCase3", "10+5", []int{15}},
 	}
 
 	//	开始测试
@@ -32,14 +34,29 @@ func TestSolution(t *testing.T) {
 					t.Fatalf("expected: %v, but got: %v, with inputs: %v", c.expect, got, c.inputs)
 				}
 			}
+
+			got = diffWaysToCompute2(c.inputs)
+			sort.Ints(got)
+			if len(got) != len(c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v", c.expect, got, c.inputs)
+			}
+			m = make(map[int]int)
+			for v := range got {
+				m[v]++
+			}
+			for v := range c.expect {
+				if _, ok := m[v]; !ok {
+					t.Fatalf("expected: %v, but got: %v, with inputs: %v", c.expect, got, c.inputs)
+				}
+			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }