Leetcode#12 integer-to-roman

https://leetcode.com/problems/integer-to-roman/submissions/

* 12.php

<?php

class Solution {
    
    // a[0] > a[1] > a[2] ...
    private static function indexLessThan($a, $ans, $start=0) {
        $n = count($a);
        for ($i = $start; $i < $n; $i++) {
            if ($a[$i] <= $ans) {
                return $i;
            }
        }
        return -1;
    }

    /**
     * @param Integer $num
     * @return String
     */
    public function intToRoman($num) {
        $a = [1000, 900, 500, 400,  100,  90,  50,  40, 10,  9,  5,    4,    1];
        $b = ['M', 'CM', 'D', 'CD', 'C', 'XC', 'L','XL','X','IX','V', 'IV', 'I'];

        $r = [];
        while (($i = self::indexLessThan($a, $num, 0)) >= 0) {
            $num -= $a[$i];
            array_push($r, $b[$i]);
        }
        $s = "";
        foreach ($r as $t) {
            $s .= $t;
        }
        return $s;
    }
}

* 测试代码

$s = new Solution();
// 27 XXVII
// 1994 MCMXCIV
$cases = [3, 12, 27, 4, 19, 58, 1994];
foreach ($cases as $case) {
    printf("%d => %s\n", $case, $s->intToRoman($case));   
}
 

运行结果

$ php 12.php
3 => III
12 => XII
27 => XXVII
4 => IV
19 => XIX
58 => LVIII
1994 => MCMXCIV
 

有不必要的数组造成内存开销，直接拼接字符串即可。

而且数字总是从大往下匹配，所以只需要一次循环。

<?php

class Solution {

    /**
     * @param Integer $num
     * @return String
     */
    public function intToRoman($num) {
        $a = [1000, 900, 500, 400,  100,  90,  50,  40, 10,  9,  5,    4,    1];
        $b = ['M', 'CM', 'D', 'CD', 'C', 'XC', 'L','XL','X','IX','V', 'IV', 'I'];

        $s = "";
        $i = 0;
        while ($num > 0) {
            if ($num >= $a[$i]) {
                $num -= $a[$i];
                $s .= $b[$i];
            } else {
                $i += 1;
            }
        }
        return $s;
    }
}

$s = new Solution();
// 27 XXVII
// 1994 MCMXCIV
$cases = [3, 12, 27, 4, 19, 58, 1994];
foreach ($cases as $case) {
    printf("%d => %s\n", $case, $s->intToRoman($case));
}

https://leetcode.com/problems/integer-to-roman/submissions/

 

用Java写:

package com.leetcode.integerToRoman;

public class Solution {
	
    public String intToRoman(int num) {
        int[] a =    {1000, 900, 500, 400, 100, 90,  50, 40,  10,  9,   5, 4, 1};
        String[] b = {"M", "CM", "D", "CD", "C","XC","L","XL","X","IX","V","IV", "I"};
        StringBuilder sb = new StringBuilder();
        
        int i = 0;        
        while (num > 0) {
        	if (num >= a[i]) {
        		num -= a[i];
        		sb.append(b[i]);
        	} else {
        		i++;
        	}
        }
        
        return sb.toString();
    }

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Solution s = new Solution();
		int[] cases = {3, 12, 27, 4, 19, 58, 1994};
		for (int i = 0; i < cases.length; i++) {
			System.out.printf("%d => %s\n", cases[i], s.intToRoman(cases[i]));
		}
	}

}

相关文章: Leetcode#13. Roman to Integer

 

来源：CSDN

作者：fareast_mzh

链接：https://blog.csdn.net/fareast_mzh/article/details/103928100