package main
import "fmt"
func lengthOfNonRepeatingSubStr(s string) int {
lastOccurred := make(map[rune]int)
start := 0
maxLength := 0
for i, ch := range []rune(s) {
if lastI, ok := lastOccurred[ch]; ok && lastI >= start {
start = lastI + 1
}
if i-start+1 > maxLength {
maxLength = i - start + 1
}
lastOccurred[ch] = i
}
return maxLength
}
func main() {
fmt.Println(lengthOfNonRepeatingSubStr("123123"))
}
随便写一个名字叫nonrepeat.go的文件,然后再写了一个nonrepeat_test.go
package main
import "testing"
func BenchmarkLengthOfNonRepeatingSubStr(b *testing.B) {
for i := 0; i < b.N; i++ {
if lengthOfNonRepeatingSubStr("123123") != 3 {
b.Errorf("正确的值是:%d",3)
}
}
}
然后执行:
go test -bench . -cpuprofile cpu.out goos: darwin goarch: amd64 pkg: gopcp.v2/chapter7/nonrepeat BenchmarkLengthOfNonRepeatingSubStr-4 10000000 225 ns/op PASS ok gopcp.v2/chapter7/nonrepeat 2.646s
nonrepeat go tool pprof cpu.out Type: cpu Time: Apr 16, 2019 at 6:53pm (CST) Duration: 2.64s, Total samples = 2.28s (86.48%) Entering interactive mode (type "help" for commands, "o" for options) (pprof)
mac 上面还需要安装图形化的界面工具 https://www.macports.org/install.php ,实在不行参考 https://blog.csdn.net/qq_36847641/article/details/78224910 这个安装盒子
(pprof) web Failed to execute dot. Is Graphviz installed? Error: exec: "dot": executable file not found in $PATH (pprof)
上面分析得出map 访问占用的性能比较高,可以换个用 slice 处理