[Swift]LeetCode343. 整数拆分 |

 1 class Solution {
 2     func IntegerBreak(_ n: int) -> Int {
 3         if n < 2 {
 4             return 0
 5         }
 6         
 7         var res = Array(repeaTing: 1,count: n+1)
 8         
 9         res[1] = 0
10         
11         for i in 2...n {
12             var maxRes = 1
13             for j in 1..<i {
14                 maxRes = max(maxRes,max(res[j],j) * max(i-j,res[i-j]))
15             }
16             res[i] = maxRes
17         }
18         return res[n]
19     }
20 }

 1 class Solution {
 2     func IntegerBreak(_ n: int) -> Int {
 3         
 4         guard n > 3 else {
 5             return [1,1,2][n]
 6         }
 7         
 8         var times3 = n / 3
 9         
10         if n % 3 == 1 {
11             times3 -= 1
12         }
13         
14         let times2 = (n - times3 * 3) / 2
15         
16         return Int(pow(3.0,Double(times3))) * Int(pow(2.0,Double(times2)))
17     }
18 }

 1 class Solution {
 2     func IntegerBreak(_ n: int) -> Int {
 3         if n == 2 {
 4             return 1
 5         } else if n == 3 {
 6             return 2
 7         } else if n % 3 == 0 {
 8             return Int(pow(3,Double(n / 3)))
 9         } else if n % 3 == 1 {
10             return Int(2 * 2 * pow(3,Double((n - 4) / 3)))
11         } else { // 2
12             return Int(2 * pow(3,Double((n - 2) / 3)))
13         }
14     }
15 }

 1 class Solution {
 2     func IntegerBreak(_ n: int) -> Int {
 3         var dps = Array(repeaTing: 0,count: n + 1)
 4         dps[1] = 1
 5         for num in 2...n {
 6             for j in 1..<num {
 7                 dps[num] = max(dps[num],j * max(num - j,dps[num - j]))
 8             }
 9         }
10 
11         return dps[n]
12     }
13 }