Project Euler：Problem 67 Maximum path sum II

标签：project euler   c++   动态规划   

By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23.

3
7 4
2 4 6
8 5 9 3

That is, 3 + 7 + 4 + 9 = 23.

Find the maximum total from top to bottom in triangle.txt (right click and ‘Save Link/Target As...‘), a 15K text file containing a triangle with one-hundred rows.

NOTE: This is a much more difficult version of Problem 18. It is not possible to try every route to solve this problem, as there are 2⁹⁹ altogether! If you could check one trillion (10¹²) routes every second it would take over twenty billion years to check them all. There is an efficient algorithm to solve it. ;o)

动态规划

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


int main()
{
	ifstream input;
	string line;
	input.open("triangle.txt");
	vector<vector<int>>data;
	vector<int>num;
	while (getline(input, line))
	{
		num.clear();
		int tmp = 0;
		for (int i = 0; i < line.length(); i++)
		{
			if (i % 3 == 2)
				continue;
			if (i % 3 == 1)
			{
				tmp = tmp * 10 + line[i] - '0';
				num.push_back(tmp);
				tmp = 0;
			}
			else
				tmp += line[i] - '0';
		}
		data.push_back(num);
	}
	input.close();
	
	for (int i = data.size() - 2; i >= 0; i--)
	{
		for (int j = 0; j < data[i].size(); j++)
		{
			data[i][j] = data[i + 1][j]>data[i + 1][j + 1] ? data[i][j] + data[i + 1][j] : data[i][j] + data[i + 1][j + 1];
		}
	}
	cout << data[0][0] << endl;
	system("pause");
	return 0;
}

Project Euler：Problem 67 Maximum path sum II

标签：project euler   c++   动态规划   

原文地址：http://blog.csdn.net/youb11/article/details/46900547