update

oj/tencent-2017-autumn/geohash.go

@@ -7,11 +7,11 @@ import (
 func main() {
 	var n int
 	fmt.Scan(&n)
-	val, beg, end := n, -90, 90
+	beg, end := -90, 90
 	code := make([]rune, 6)
 	for i := 0; i < 6; i++ {
 		mid := (beg + end) / 2
-		if mid <= val {
+		if mid <= n {
 			code[i] = '1'
 			beg = mid
 		} else {

oj/tencent-2017-autumn/prime-pair.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"fmt"
-	"math"
 )
 
 func main() {
@@ -10,8 +9,7 @@ func main() {
 	fmt.Scan(&n)
 	sieve := make([]bool, n+1)
 	prime := make([]int, 0)
-	sqrt := int(math.Sqrt(float64(n)))
-	for i := 2; i <= sqrt; i++ {
+	for i := 2; i*i <= n; i++ {
 		if sieve[i] {
 			continue
 		}