Created
November 5, 2018 09:46
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Fast IO for scanning input via STDIn for competitive programming in Golang
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| /** | |
| * This snippet assumes large input and large output and that all the input contains numbers in the form of string | |
| */ | |
| package main | |
| import ( | |
| "bufio" | |
| "io/ioutil" | |
| "os" | |
| "strconv" | |
| ) | |
| var bytes []byte | |
| var l, max int | |
| /** | |
| * Perform Quick Scan of 1 data(with no spaces in-between) on the buffered input | |
| */ | |
| func fastScan() int { | |
| b := bytes[l] | |
| // Check if the bytes is not a number | |
| for b < 48 || b > 57 { | |
| l++ | |
| b = bytes[l] | |
| } | |
| result := 0 | |
| for 47 < b && b < 58 { | |
| result = (result << 3) + (result << 1) + int(b-48) | |
| l++ | |
| if l > max { | |
| return result | |
| } | |
| b = bytes[l] | |
| } | |
| return result | |
| } | |
| func main() { | |
| // Read all the input into Buffer | |
| bytes, _ = ioutil.ReadAll(bufio.NewReader(os.Stdin)) | |
| max = len(bytes) - 1 | |
| // Create a write buffer directed to STDOUT | |
| ws := bufio.NewWriter(os.Stdout) | |
| // Read the first param | |
| t := fastScan() | |
| for t > 0 { | |
| t-- | |
| ws.WriteString(strconv.Itoa(t) + "\n") | |
| } | |
| ws.Flush() | |
| } |
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