Project Euler：Problem 42 Coded triangle numbers

最新推荐文章于 2021-03-03 09:12:36 发布

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最新推荐文章于 2021-03-03 09:12:36 发布

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原文链接：http://www.cnblogs.com/llguanli/p/6919726.html

本文介绍了一种通过计算单词值来判断其是否为三角数的方法，并使用C++编程实现了一个程序，该程序读取包含近两千个常见英语单词的文件，并统计其中有多少个单词是三角数单词。

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The n^th term of the sequence of triangle numbers is given by, t_n = ½n(n+1); so the first ten triangle numbers are:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...

By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 = t₁₀. If the word value is a triangle number then we shall call the word a triangle word.

Using words.txt (right click and 'Save Link/Target As...'), a 16K text file containing nearly two-thousand common English words, how many are triangle words?

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

map<int, int>mp;
void triangle()
{
	for (int i = 1; i < 10000; i++)
	{
		mp[i*(i + 1) / 2] = 1;
	}
}

int main()
{
	triangle();
	ifstream input;
	input.open("words.txt");
	char s[16347];
	while (!input.eof())
		input >> s;
	input.close();
	vector<string> name;
	string tm;
	for (int i = 1; i <= 16346; i++)
	{
		if (s[i] >= 65 && s[i] <= 90 && s[i + 1] == '"')
		{
			tm = tm + s[i];
			name.push_back(tm);
			tm.clear();
		}
		else if (s[i] == ',' || s[i] == '"')
			continue;
		else
			tm = tm + s[i];
	}
	int ans = 0;
	for (int i = 0; i < name.size(); i++)
	{
		int sum = 0;
		for (int j = 0; j < name[i].length(); j++)
		{
			sum = sum + name[i][j] - 'A' + 1;
		}
		if (mp[sum] == 1)
			ans++;
	}
	cout << ans << endl;
	system("pause");
	return 0;
}

转载于:https://www.cnblogs.com/llguanli/p/6919726.html