剑指offer——15剪绳子

 1 class Solution {
 2 public:
 3     int cutRope(int number) {
 4         if (number <= 1)return 0;
 5         if (number < 5)return (number / 2)*(number - number / 2);//因为至少要分为2段
 6         vector<int>dp(number + 1, 0);
 7         dp[0] = 0, dp[1] = 1, dp[2] = 2, dp[3] = 3;
 8         int maxN = 0;
 9         for (int i = 4; i <= number; ++i)
10         {
11             maxN = 0;
12             for (int j = 1; j <= i / 2; ++j)
13             {
14                 int temp = dp[j] * dp[i - j];
15                 maxN = maxN > temp ? maxN : temp;
16                 dp[i] = maxN;
17             }
18         }
19         return dp[number];
20     }
21 };

 1 class Solution {
 2 public:
 3     int cutRope(int number) {
 4         if (number <= 1)return 0;
 5         if (number < 5)return (number / 2)*(number - number / 2);//因为至少要分为2段
 6         int n3 = number / 3;//3的个数
 7         if (number % 3 == 1)//最后剪的一段为4时，不要剪成3-1，要剪成2-2
 8             n3--;
 9         int n2 = (number - 3 * n3) / 2;//2的个数
10         return pow(3, n3)*pow(2, n2);
11     }
12 };