getLongest

func main() {

   fmt.Print(getLongest("111131111"))

}

func getLongest(input string) string {

   arr := make([][]bool, len(input))
   for i := range arr {
      arr[i] = make([]bool, len(input))
   }
   r := input[0:1]
   for i := 0; i < len(input); i++ {
      arr[i][i] = true      if i != len(input)-1 && input[i] == input[i+1] {
         r = input[i : i+1]
         arr[i][i+1] = true      }
   }

   for lenght := 3; lenght <= len(input); lenght++ {
      for i := 0; i < len(input); i++ {
         j := i + lenght - 1         if j < len(input) && isPar(i, j, input, arr) {
            arr[i][j] = true            r = input[i : j+1]
         }
      }
   }

   return r
}

func isPar(i, j int, s string, arr [][] bool) bool {
   if i == j {
      arr[i][j] = true      return true   } else {
      if i+1 == j && s[i] == s[j] {
         arr[i][j] = true         return true      } else {
         if s[i] == s[j] && arr[i+1][j-1] == true {
            arr[i][j] = true            return true         }

      }

   }

   return false}