Return Index of Matching Closing Bracket in Go

The challenge

In this challenge, you will be given a string with brackets and an index of an opening bracket and your task will be to return the index of the matching closing bracket. Both the input and returned index are 0-based. An opening brace will always have a closing brace. Return an error if there is no answer.

Examples:

solve("((1)23(45))(aB)", 0) = 10 // the opening brace at index 0 matches the closing brace at index 10 solve("((1)23(45))(aB)", 1) = 3 solve("((1)23(45))(aB)", 2) = -1 // there is no opening bracket at index 2, so return -1 solve("((1)23(45))(aB)", 6) = 9 solve("((1)23(45))(aB)", 11) = 14 solve("((>)|?(*'))(yZ)", 11) = 14
Code language: Go (go)

Input will consist of letters, numbers, and special characters, but no spaces. The only brackets will be ( and ).

The solution in Golang

Option 1:

package solution; import ("errors") func Solution(s string, i uint) (uint, error) { if s[i] == '(' { d := 0; for j := i+1; j < uint(len(s)); j++ { c := s[j]; switch { case d==0 && c==')': return j, nil; case c=='(': d++; case d>0 && c==')': d--; } } } return 0, errors.New(""); }
Code language: Go (go)

Option 2:

package solution import "errors" func Solution(s string, i uint) (uint, error) { if string(s[i])!="(" {return 0, errors.New("Not an opening bracket")} o := 1 for k := i+1 ; k < uint(len(s)) ; k++ { c := string(s[k]) if c==")" { o-- if o==0 {return k, nil} } else if c=="(" {o++} } return 0, errors.New("Not an opening bracket") }
Code language: Go (go)

Option 3:

package solution import "errors" func Solution(str string, idx uint) (uint, error) { if str[idx] != '(' { return 0, errors.New("Not an opening bracket") } var stack []uint for i, val := range str { switch val { case '(': stack = append(stack, uint(i)) // stack push case ')': n := len(stack)-1 pop := stack[n] // stack pop stack = stack[:n] if pop == idx { return uint(i), nil } } } return 0, errors.New("No solution") }
Code language: Go (go)

Test cases to validate our solution

package solution_test import ( . "github.com/onsi/ginkgo" . "github.com/onsi/gomega" ) var _ = Describe("Sample tests for Solution", func() { It("should test that Solution returns the correct value", func() { Expect(Solution("((1)23(45))(aB)", 0)).To(Equal(uint(10))) Expect(Solution("((1)23(45))(aB)", 1)).To(Equal(uint(3))) _, err := Solution("((1)23(45))(aB)", 2) Expect(err).To(HaveOccurred()) Expect(Solution("((1)23(45))(aB)", 6)).To(Equal(uint(9))) Expect(Solution("((1)23(45))(aB)", 11)).To(Equal(uint(14))) Expect(Solution("(g(At)IO(f)(tM(qk)YF(n)Nr(E)))", 11)).To(Equal(uint(28))) Expect(Solution("(g(At)IO(f)(tM(qk)YF(n)Nr(E)))", 0)).To(Equal(uint(29))) Expect(Solution("(>_(va)`?(h)C(as)(x(hD)P|(fg)))", 19)).To(Equal(uint(22))) }) })
Code language: Go (go)
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