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:
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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
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Input will consist of letters, numbers, and special characters, but no spaces. The only brackets will be ( and ).
The solution in Golang
Option 1:
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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("");
}
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Option 2:
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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")
}
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Option 3:
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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")
}
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Test cases to validate our solution
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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)))
})
})
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