LeetCode 343

Integer Break

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.

For example, given n = 2, return 1 (2 = 1 + 1); given n = 10, return 36 (10 = 3 + 3 + 4).

Note: you may assume that n is not less than 2.

Hint:

There is a simple O(n) solution to this problem.
You may check the breaking results of n ranging from 7 to 10 to discover the regularities.

 1 /*************************************************************************
 2     > File Name: LeetCode343.c
 3     > Author: Juntaran
 4     > Mail: [email protected]
 5     > Created Time: Tue 10 May 2016 04:17:35 PM CST
 6  ************************************************************************/
 7
 8 /*************************************************************************
 9
10     Integer Break
11
12     Given a positive integer n, break it into the sum of at least two positive integers
13     and maximize the product of those integers. Return the maximum product you can get.
14
15     For example, given n = 2, return 1 (2 = 1 + 1); given n = 10, return 36 (10 = 3 + 3 + 4).
16
17     Note: you may assume that n is not less than 2.
18
19     Hint:
20
21     There is a simple O(n) solution to this problem.
22     You may check the breaking results of n ranging from 7 to 10 to discover the regularities.
23
24  ************************************************************************/
25
26 #include<stdio.h>
27
28 int integerBreak( int n )
29 {
30     if( n <= 2 )
31     {
32         return 1;
33     }
34     if( n == 3 )
35     {
36         return 2;
37     }
38     int ret = 1;
39     while( n > 4 )
40     {
41         ret *= 3;
42         n -= 3;
43     }
44     return ret*n;
45 }
46
47 int main()
48 {
49     int n = 7;
50     int ret = integerBreak(n);
51     printf("%d\n",ret);
52
53     return 0;
54 }