Created
January 7, 2020 22:56
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Figure out if the phone number is correct without asking for it directly.
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// This program provides an answer for one of the Google interview questions described here: | |
// https://www.businessinsider.com/answers-to-google-interview-questions-2011-11#you-need-to-check-that-your-friend-bob-has-your-correct-phone-number-10 | |
package main | |
import ( | |
"fmt" | |
"strings" | |
) | |
func main() { | |
collisions := make(map[uint][]string) | |
for _, p := range [...][10]rune{ | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '1'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '2'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '3'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '4'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '5'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '6'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '7'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '8'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '9'}, | |
{'2', '1', '1', '1', '1', '1', '1', '1', '1', '1'}, | |
{'1', '2', '1', '1', '1', '1', '1', '1', '1', '1'}, | |
{'1', '1', '2', '1', '1', '1', '1', '1', '1', '1'}, | |
{'1', '1', '1', '2', '1', '1', '1', '1', '1', '1'}, | |
{'1', '1', '1', '1', '2', '1', '1', '1', '1', '1'}, | |
{'1', '1', '1', '1', '1', '2', '1', '1', '1', '1'}, | |
{'1', '1', '1', '1', '1', '1', '2', '1', '1', '1'}, | |
{'1', '1', '1', '1', '1', '1', '1', '2', '1', '1'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '2', '1'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '2'}, | |
{'9', '1', '1', '1', '1', '1', '1', '1', '1', '1'}, | |
{'1', '9', '1', '1', '1', '1', '1', '1', '1', '1'}, | |
{'1', '1', '9', '1', '1', '1', '1', '1', '1', '1'}, | |
{'1', '1', '1', '9', '1', '1', '1', '1', '1', '1'}, | |
{'1', '1', '1', '1', '9', '1', '1', '1', '1', '1'}, | |
{'1', '1', '1', '1', '1', '9', '1', '1', '1', '1'}, | |
{'1', '1', '1', '1', '1', '1', '9', '1', '1', '1'}, | |
{'1', '1', '1', '1', '1', '1', '1', '9', '1', '1'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '9', '1'}, | |
{'1', '1', '1', '1', '1', '1', '1', '1', '1', '9'}, | |
} { | |
phone, sum := Phone(p), Sum(p) | |
fmt.Printf("%s - %d\n", phone, sum) | |
if phones, ok := collisions[sum]; ok { | |
phones = append(phones, phone) | |
collisions[sum] = phones | |
} else { | |
collisions[sum] = []string{phone} | |
} | |
} | |
for k, v := range collisions { | |
if len(v) > 1 { | |
fmt.Printf("Found collision on %d for: %s\n", k, strings.Join(v, ", ")) | |
} | |
} | |
} | |
func Sum(digits [10]rune) uint { | |
res := uint(0) | |
for _, n := range digits { | |
res += (res + uint(n-'0')) * 10 | |
} | |
return res | |
} | |
func Phone(digits [10]rune) string { | |
return fmt.Sprintf("(%s) %s-%s", string(digits[:3]), string(digits[3:6]), string(digits[6:])) | |
} |
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Live code - https://play.golang.org/p/HWtXPNNO22B
Output: