编程算法 - 丑数 代码(C)

丑数 代码(C)

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题目: 我们把只包含因子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.

可以设置一个数组包含所需要的丑数, 依次比较乘以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