Leetcode brush problem, summary, record, Memo 343

Source: Internet
Author: User

leetcode343Integer break

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

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

Note: You may assume this n is not less than 2.

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    Credits:
    Special thanks to @jianchao. Li.fighter for adding the problem and creating all test cases.

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    using dynamic programming, we can find a rule by observing that the maximum value of n is either 1 on the basis of n-1, Either add 2 on top of the n-2. First, if it is based on the results of n-1, if you simply add a 1 in the n-1 array, the result is constant, so you need to add 1 to an element in the n-1 array, this 1 is best added to the smallest number in the n-1 array, so the product is the largest. If it is based on n-2, simply add a 2 to the array of n-2, and the one that evaluates to the maximum in these 2 arrays is the result of N. Suppose that the DP array is an array of each number that holds each number, such as dp[10] = {3, 3, 4}. The work to be done before the recursive formula, Dp[n-2].push_back (2); Sort (Dp[n-2].begin (), Dp[n-2].end ());  dp[n-1][0]++;  sort (Dp[n-1].begin (), Dp[n-1].end ()); Recursive formula: dp[n] = func (dp[n-2]) > func (dp[n-1])?  Dp[n-2]: dp[n-1]; Func is an auxiliary function that computes the result of an array and sorts it in order to serve the subsequent computations. You can view the code in detail.

    Class Solution {Public:int function (Vector<int> t) {int sum = 1;        for (int i = 0; i < t.size (); ++i) {sum *= t[i];    } return sum;        } int Integerbreak (int n) {if (n <= 0) {return 0;        } if (n = = 1) {return 1;                } vector<vector<int> > DP (n + 1, vector<int> ());        Dp[1].push_back (1);        Dp[2].push_back (1);                Dp[2].push_back (1);            for (int i = 3; I < dp.size (); ++i) {vector<int> temp1 = dp[i-2];            Temp1.push_back (2);            Vector<int> temp2 = dp[i-1];            temp2[0]++;            Sort (Temp1.begin (), Temp1.end ());                        Sort (Temp2.begin (), Temp2.end ());            if (function (TEMP1) > function (TEMP2)) {dp[i] = Temp1; } else {DP[I] = TEMP2;            }} return function (Dp[n]); }};


    Leetcode brush problem, summary, record, Memo 343

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