sort.SearchInts()はSort済みじゃないと動かない ref: http://qiita.com/inaba178/items/795c2e18078c4063a264

search1.go

package main

import (
    "fmt"
    "sort"
)

func main() {
    a := []int{10, 9, 8, 7, 6, 5, 4, 3, 2, 1}
    res := sort.SearchInts(a, 7)
    fmt.Println("array:", a)
    fmt.Println("result:", res)
}

search2.go

package main

import (
    "fmt"
    "sort"
)

func main() {
    a := []int{10, 9, 8, 7, 6, 5, 4, 3, 2, 1}
    sort.Ints(a)
    res := sort.SearchInts(a, 7)
    fmt.Println("array:", a)
    fmt.Println("result:", res)
}