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package stringsearch
func (s string, p string) int { suffix, prefix := initGS(p)
bc := initBC(p) for i := 0; i < len(s)-len(p); { j := len(p) - 1
for ; j >= 0; j-- { if s[i+j] != p[j] { break } }
if j < 0 { return i }
x := j - bc[s[i+j]]
y := 1 if j < len(p)-1 { y = moveGS(j, len(p), suffix, prefix) }
ret := x if y > x { ret = y } i = i + ret } return -1 }
func initBC(pattern string) []int { bc := make([]int, 256) for r := 0; r < 255; r++ { bc[r] = -1 }
for idx, v := range []byte(pattern) { bc[v] = idx }
return bc }
func initGS(pattern string) ([]int, []bool) { suffix := make([]int, len(pattern)) prefix := make([]bool, len(pattern)) for r := 0; r < len(pattern); r++ { suffix[r] = -1 }
for i := 0; i < len(pattern)-1; i++ { j := i k := 0 for j >= 0 && pattern[j] == pattern[len(pattern)-1-k] { k++ suffix[k] = j j-- }
if j < 0 { prefix[k] = true } }
return suffix, prefix }
func moveGS(j int, m int, suffix []int, prefix []bool) int { k := m - 1 - j if suffix[k] != -1 { return j - suffix[k] + 1 } else { for r := j + 2; r <= m-1; r++ { if prefix[m-r] { return r } } }
return m }
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