欧拉计画:413

本文介绍了欧拉计画:413的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试使用蛮力解决最新的欧拉计划问题(我知道这不是最好的解决方案，但是直到我弄清楚我弄错了什么地方，我才使用它).

I'm trying to solve the latest Project Euler problem using brute force ( I know it's not the best solution, but till I figure out, where I'm mistaken, I'll just use that ).

我不明白，我到底在做什么错.我敢肯定我会生成正确的数字，但是提供的数字仍然是错误的结果:

I can't understand, what exactly am I doing wrong here. I'm pretty sure that I generate the correct numbers, but the outcome is still wrong with the provided numbers:

function number_split( $nb ) { GLOBAL $arr; $length = strlen( $nb ); if( $length == 1 ) return true; $count = 0; for( $i=1; $i<$length; $i++ ) { for( $j=0; $j<=$length-$i; $j++ ) { $temp = substr( $nb, $j, $i ); if( $temp % $length == 0 ) { $count++; if( $count > 1 ) return false; } } } return ( $count == 1 ); } $lim = 3; $res = 0; $start = gmp_strval( gmp_pow( 10, $lim-1 ) ); $end = gmp_strval( gmp_pow( 10, $lim ) ); for( $i=$start; $i<$end; $i++ ) { $res += number_split( $i ); } echo $res;

我得到378，应该有389.我在这里做错什么了?

I get 378 where there should be 389. What am I doing wrong here?

我不想要答案，只是想知道我的逻辑错在哪里.

I don't want an answer, just a hitch on where my logic is wrong.

问题:

推荐答案

您只查看3位数字，但需要查看10 ^ 3以下的所有数字，包括1位和2位数字.换句话说，$start应该是1.

You are only looking at 3-digit numbers, but you need to look at all numbers under 10^3, which includes 1-digit and 2-digit numbers. In other words, $start should be 1.

此外，您不会查看整个原始字符串的子字符串，因为$i(子字符串的长度)只能运行到$length - 1.

Additionally, you aren't looking at the substring which is the entire original string, because $i (the length of the substring) only runs up to $length - 1.