数丑陋 代码(C)

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题目: 我们把仅仅包括因子2, 3 和 5的数称作丑数. 求按从小到大的顺序的第5个丑数.

能够设置一个数组包括所须要的丑数, 依次比較乘以2, 乘以3, 乘以5的最小的数, 最后返回结果.

如第5个丑数是5, 如1, 2, 3, 4(2*2), 5均是丑数.

代码:

/*

 * main.cpp

 *

 *  Created on: 2014.6.12

 *      Author: Spike

 */

/*eclipse cdt, gcc 4.8.1*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

int Min(int number1, int number2, int number3) {

	int min = (number1 < number2) ? number1 : number2;

	min = (min < number3) ? min : number3;

	return min;

}

int GetUglyNumber(int index) {

	if (index <= 0)

		return 0;

	int* pUglyNumbers = new int[index];

	pUglyNumbers[0] = 1;

	int nextUglyIndex = 1;

	int* pMultiply2 = pUglyNumbers;

	int* pMultiply3 = pUglyNumbers;

	int* pMultiply5 = pUglyNumbers;

	while (nextUglyIndex < index) {

		int min = Min(*pMultiply2*2, *pMultiply3*3, *pMultiply5*5);

		pUglyNumbers[nextUglyIndex] = min;

		while (*pMultiply2*2 <= pUglyNumbers[nextUglyIndex])

			++pMultiply2;

		while (*pMultiply3*3 <= pUglyNumbers[nextUglyIndex])

			++pMultiply3;

		while (*pMultiply5*5 <= pUglyNumbers[nextUglyIndex])

			++pMultiply5;

		++nextUglyIndex;

	}

	int ugly = pUglyNumbers[nextUglyIndex-1];

	delete[] pUglyNumbers;

	return ugly;

}

int main(void)

{

    int num = 5;

    int result = GetUglyNumber(num);

    printf("result = %d\n", result);

    return 0;

}

输出:

result = 5