[Swift]LeetCode343. 整数拆分 |_app

概述Given a positive integer n, break it into the sum of at least two positive integers and maximize the product of those integers. Return the maximum product you can get. Example 1: Input: 2Output: 1 E

Given a positive integer n,break it into the sum of at least two positive integers and maximize the product of those integers. Return the maximum product you can get.

Example 1:

input: 2Output: 1 Explanation: 2 = 1 + 1,1 × 1 = 1.

Example 2:

input: 10Output: 36 Explanation: 10 = 3 + 3 + 4,3 × 3 × 4 = 36.

Note: You may assume that n is not less than 2 and not larger than 58.

给定一个正整数 n，将其拆分为至少两个正整数的和，并使这些整数的乘积最大化。返回你可以获得的最大乘积。

示例 1:

输入: 2输出: 1解释: 2 = 1 + 1,1 × 1 = 1。

示例 2:

输入: 10输出: 36解释: 10 = 3 + 3 + 4,3 × 3 × 4 = 36。

说明: 你可以假设 n 不小于 2 且不大于 58。

8ms

 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] = 010         11         for i in 2...n {12             var maxRes = 113             for j in 1..<i {14                 maxRes = max(maxRes,max(res[j],j) * max(i-j,res[i-j]))15             }16             res[i] = maxRes17         }18         return res[n]19     }20 }

8ms

 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 -= 112         }13         14         let times2 = (n - times3 * 3) / 215         16         return Int(pow(3.0,Double(times3))) * Int(pow(2.0,Double(times2)))17     }18 }

16ms

 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 { // 212             return Int(2 * pow(3,Double((n - 2) / 3)))13         }14     }15 }

24ms

 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 }