Update README.md

Author: yanglbme

solution/3300-3399/3348.Smallest Divisible Digit Product II/README.md

@@ -107,7 +107,138 @@ tags:
 #### Go
 
 ```go
-
+func smallestNumber(num string, t int64) string {
+	primeCount, isDivisible := getPrimeCount(t)
+	if !isDivisible {
+		return "-1"
+	}
+
+	factorCount := getFactorCount(primeCount)
+	if sumValues(factorCount) > len(num) {
+		return construct(factorCount)
+	}
+
+	primeCountPrefix := getPrimeCountFromString(num)
+	firstZeroIndex := strings.Index(num, "0")
+	if firstZeroIndex == -1 {
+		firstZeroIndex = len(num)
+		if isSubset(primeCount, primeCountPrefix) {
+			return num
+		}
+	}
+
+	for i := len(num) - 1; i >= 0; i-- {
+		d := int(num[i] - '0')
+		primeCountPrefix = subtract(primeCountPrefix, kFactorCounts[d])
+		spaceAfterThisDigit := len(num) - 1 - i
+		if i > firstZeroIndex {
+			continue
+		}
+		for biggerDigit := d + 1; biggerDigit < 10; biggerDigit++ {
+			factorsAfterReplacement := getFactorCount(
+				subtract(subtract(primeCount, primeCountPrefix), kFactorCounts[biggerDigit]),
+			)
+			if sumValues(factorsAfterReplacement) <= spaceAfterThisDigit {
+				fillOnes := spaceAfterThisDigit - sumValues(factorsAfterReplacement)
+				return num[:i] + strconv.Itoa(biggerDigit) + strings.Repeat("1", fillOnes) + construct(factorsAfterReplacement)
+			}
+		}
+	}
+
+	factorsAfterExtension := getFactorCount(primeCount)
+	return strings.Repeat("1", len(num)+1-sumValues(factorsAfterExtension)) + construct(factorsAfterExtension)
+}
+
+var kFactorCounts = map[int]map[int]int{
+	0: {}, 1: {}, 2: {2: 1}, 3: {3: 1}, 4: {2: 2},
+	5: {5: 1}, 6: {2: 1, 3: 1}, 7: {7: 1}, 8: {2: 3}, 9: {3: 2},
+}
+
+func getPrimeCount(t int64) (map[int]int, bool) {
+	count := map[int]int{2: 0, 3: 0, 5: 0, 7: 0}
+	for _, prime := range []int{2, 3, 5, 7} {
+		for t%int64(prime) == 0 {
+			t /= int64(prime)
+			count[prime]++
+		}
+	}
+	return count, t == 1
+}
+
+func getPrimeCountFromString(num string) map[int]int {
+	count := map[int]int{2: 0, 3: 0, 5: 0, 7: 0}
+	for _, d := range num {
+		for prime, freq := range kFactorCounts[int(d-'0')] {
+			count[prime] += freq
+		}
+	}
+	return count
+}
+
+func getFactorCount(count map[int]int) map[int]int {
+	res := map[int]int{}
+	count8 := count[2] / 3
+	remaining2 := count[2] % 3
+	count9 := count[3] / 2
+	count3 := count[3] % 2
+	count4 := remaining2 / 2
+	count2 := remaining2 % 2
+	count6 := 0
+	if count2 == 1 && count3 == 1 {
+		count2, count3 = 0, 0
+		count6 = 1
+	}
+	if count3 == 1 && count4 == 1 {
+		count2 = 1
+		count6 = 1
+		count3, count4 = 0, 0
+	}
+	res[2] = count2
+	res[3] = count3
+	res[4] = count4
+	res[5] = count[5]
+	res[6] = count6
+	res[7] = count[7]
+	res[8] = count8
+	res[9] = count9
+	return res
+}
+
+func construct(factors map[int]int) string {
+	var res strings.Builder
+	for digit := 2; digit < 10; digit++ {
+		res.WriteString(strings.Repeat(strconv.Itoa(digit), factors[digit]))
+	}
+	return res.String()
+}
+
+func isSubset(a, b map[int]int) bool {
+	for key, value := range a {
+		if b[key] < value {
+			return false
+		}
+	}
+	return true
+}
+
+func subtract(a, b map[int]int) map[int]int {
+	res := make(map[int]int, len(a))
+	for k, v := range a {
+		res[k] = v
+	}
+	for k, v := range b {
+		res[k] = max(0, res[k]-v)
+	}
+	return res
+}
+
+func sumValues(count map[int]int) int {
+	sum := 0
+	for _, v := range count {
+		sum += v
+	}
+	return sum
+}
 ```
 
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