Update 0483 solution

leetcode/0483.Smallest-Good-Base/483. Smallest Good Base.go

@@ -2,34 +2,23 @@ package leetcode
 
 import (
 	"math"
+	"math/bits"
 	"strconv"
 )
 
 func smallestGoodBase(n string) string {
-	num, _ := strconv.ParseUint(n, 10, 64)
-	for bit := uint64(math.Log2(float64(num))); bit >= 1; bit-- {
-		low, high := uint64(2), uint64(math.Pow(float64(num), 1.0/float64(bit)))
-		for low < high {
-			mid := uint64(low + (high-low)>>1)
-			sum := findBase(mid, bit)
-			if sum == num {
-				return strconv.FormatUint(mid, 10)
-			} else if sum > num {
-				high = mid - 1
-			} else {
-				low = mid + 1
-			}
+	nVal, _ := strconv.Atoi(n)
+	mMax := bits.Len(uint(nVal)) - 1
+	for m := mMax; m > 1; m-- {
+		k := int(math.Pow(float64(nVal), 1/float64(m)))
+		mul, sum := 1, 1
+		for i := 0; i < m; i++ {
+			mul *= k
+			sum += mul
+		}
+		if sum == nVal {
+			return strconv.Itoa(k)
 		}
 	}
-	return strconv.FormatUint(num-1, 10)
-}
-
-// 计算 k^m + k^(m-1) + ... + k + 1
-func findBase(mid, bit uint64) uint64 {
-	sum, base := uint64(1), uint64(1)
-	for i := uint64(1); i <= bit; i++ {
-		base *= mid
-		sum += base
-	}
-	return sum
+	return strconv.Itoa(nVal - 1)
 }