面试题14：剪绳子

本题考察的是动态规划与贪心算法，有一个疑问，为何i<4时，products[i]=i。

C++版本

#include <iostream>
#include <vector>
using namespace std;

// 动态规划
int maxProductAfterCutting_solution1(int length)
{
    if(length < 2)
        return 0;
    if(length == 2)
        return 1;
    if(length == 3)
        return 2;

    int* products = new int[length + 1];
    products[1] = 1;
    products[2] = 2;
    products[3] = 3;

    int max = 0;
    for(int i = 4; i <= length; ++i)
    {
        max = 0;
        for(int j = 1; j <= i / 2; ++j)
        {
            int product = products[j] * products[i - j];
            if(max < product)
                max = product;

            products[i] = max;
        }
    }

    max = products[length];
    delete[] products;

    return max;
}

// 贪心做法
int cutRope(int number){
    if(number < 2)
        return 0;
    if(number == 2)
        return 1;
    if(number == 3)
        return 2;

    int numOf3 = number/3;
    // 当绳子最后剩下的长度等于4，需要变为2*2
    if(number - numOf3*3 == 1)
        numOf3--;
    int numOf2 = (number - numOf3*3)/2;
    return (int)(pow(3,numOf3))*(int)(pow(2,numOf2));
}

int main(){
    int a[5] = {1,2,3,4,5};
    cout<<&a[2]<<" "<<&a[3]<<endl;
    cout<<Fibonacci(6)<<endl;
    return 0;
}