how make go program recursive. i'm learning golang writing game number analyzer. i've been thinking , thinking on how , can't come working solution. here link in google playground. appreciated.
/* file record.go author: dan huckson date: 20160120 purpose: number analyzer */ package main import ( "fmt" ) type stats struct { category map[string]events } type events struct { event map[string]*event } type event struct { value int64 } func main() { winners := [][]int{ {1, 2, 3, 4, 5, 6}, {2, 4, 6, 28, 26, 39}, {1, 4, 9, 10, 26, 39}, {1, 9, 19, 29, 26, 49}, {4, 5, 6, 28, 26, 49}} keys := []string{"digits1", "digits2", "digits3", "digits4", "digits5", "digits6"} stats := new(stats) stats.category = make(map[string]events) _, key := range keys { events, ok := stats.category[key] if !ok { events = *new(events) } events.event = make(map[string]*event) stats.category[key] = events } fmt.println() _, winner := range winners { fmt.println(winner) stats.digits1("digits1", winner) stats.digits2("digits2", winner) stats.digits3("digits3", winner) stats.digits4("digits4", winner) stats.digits5("digits5", winner) stats.digits6("digits6", winner) } } func (stats *stats) record(key string, balls string) { event, ok := stats.category[key].event[balls] if !ok { event = new(event) stats.category[key].event[balls] = event } stats.category[key].event[balls].value += 1 word := "" if len(balls) > 1 { word = "balls" } else { word = "ball" } fmt.printf("%s:%s\tcount:%d\n", word, balls_to_csv(balls), stats.category[key].event[balls].value) } func (stats *stats) digits1(key string, winner []int) { := 0; < len(winner); i++ { stats.record(key, string(winner[i])) } } func (stats *stats) digits2(key string, winner []int) { := 0; < len(winner)-1; i++ { j := + 1; j < len(winner); j++ { stats.record(key, string(winner[i])+string(winner[j])) } } } func (stats *stats) digits3(key string, winner []int) { := 0; < len(winner)-2; i++ { j := + 1; j < len(winner)-1; j++ { k := j + 1; k < len(winner); k++ { stats.record(key, string(winner[i])+string(winner[j])+string(winner[k])) } } } } func (stats *stats) digits4(key string, winner []int) { := 0; < len(winner)-3; i++ { j := + 1; j < len(winner)-2; j++ { k := j + 1; k < len(winner)-1; k++ { l := k + 1; l < len(winner); l++ { stats.record(key, string(winner[i])+string(winner[j])+string(winner[k])+string(winner[l])) } } } } } func (stats *stats) digits5(key string, winner []int) { := 0; < len(winner)-4; i++ { j := + 1; j < len(winner)-3; j++ { k := j + 1; k < len(winner)-2; k++ { l := k + 1; l < len(winner)-1; l++ { m := l + 1; m < len(winner); m++ { stats.record(key, string(winner[i])+string(winner[j])+string(winner[k])+string(winner[l])+string(winner[m])) } } } } } } func (stats *stats) digits6(key string, winner []int) { := 0; < len(winner)-5; i++ { j := + 1; j < len(winner)-4; j++ { k := j + 1; k < len(winner)-3; k++ { l := k + 1; l < len(winner)-2; l++ { m := l + 1; m < len(winner)-1; m++ { n := m + 1; n < len(winner); n++ { stats.record(key, string(winner[i])+string(winner[j])+string(winner[k])+string(winner[l])+string(winner[m])+string(winner[n])) } } } } } } } func balls_to_csv(key string) string { s := "" length := len(key) := 0; < length; i++ { s += fmt.sprintf("%d,", key[i]) } return s[:len(s)-1] }
as far can tell, want recursively find combinations of winning numbers. example,
package main import "fmt" func combinations(n []int, c []int, ccc [][][]int) [][][]int { if len(n) == 0 { return ccc } if len(ccc) == 0 { ccc = make([][][]int, len(n)) } := range n { cc := make([]int, len(c)+1) copy(cc, c) cc[len(cc)-1] = n[i] ccc[len(cc)-1] = append(ccc[len(cc)-1], cc) ccc = combinations(n[i+1:], cc, ccc) } return ccc } func main() { n := []int{1, 2, 3, 4} fmt.println("winning numbers", n) fmt.println() nw := 0 w := combinations(n, nil, nil) fmt.println("winning tickets:") d := " digit : " := range w { fmt.print(i+1, d) d = " digits: " j := range w[i] { nw++ fmt.print(w[i][j], " ") } fmt.println() } fmt.println() fmt.println(nw, "winners") } output:
winning numbers [1 2 3 4] winning tickets: 1 digit : [1] [2] [3] [4] 2 digits: [1 2] [1 3] [1 4] [2 3] [2 4] [3 4] 3 digits: [1 2 3] [1 2 4] [1 3 4] [2 3 4] 4 digits: [1 2 3 4] 15 winners simplifying, can see recursion.
func combinations(n []int) { if len(n) == 0 { return } := range n { combinations(n[i+1:]) } return } the recursion terminates when len(n) == 0. in loop, i increases len(n)-1, combinations(n[i+1:]) becomes combinations(n[len(n):]), , len(n[len(n):]) == 0, terminate recursion.
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