网易有道比赛第二道题目解法（java）

Problem Statement
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双倍超立方数是指一个正整数可以正好被拆分为两种不同的a^3+b^3的方式，其中a,b均为整数且0<a<=b。对于任何一个指定的 int n, 返回所有的小于等于n的双倍超立方数的个数。
Definition
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Class:
TwiceSuperCubic
Method:
count
Parameters:
int
Returns:
int
Method signature:
int count(int n)
(be sure your method is public)
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Constraints
-
n取值范围为1到1,000,000,000(含)
Examples
0)

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1
Returns: 0

1)

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1729
Returns: 1
1729=1^3+12^3 1729=9^3+10^3
2)

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475574
Returns: 27

 

 

 

 

import java.util.Arrays;
import java.util.Vector;

public class Second {
 public static void main(String[] args) {
  Second s = new Second();
  long st = System.currentTimeMillis();
  System.out.println(s.count(475574));
  System.out.println(System.currentTimeMillis() - st);
 }

 public int count(int number) {
  Vector<Integer> vec = new Vector<Integer>();
  int max = (int) Math.cbrt(number);
  for (int i = 1; i <= max; i++) {
   for (int j = max; j > i; j--) {
    int temp = addThree(i, j);
    if (temp <= number) {
     vec.add(new Integer(temp));
    }
   }
  }
  int size = vec.size();
  int result[] = new int[size];
  for (int i = 0; i < size; i++) {
   result[i] = vec.elementAt(i).intValue();
  }

  Arrays.sort(result);

  int count = 0;
  for (int i = 0; i < result.length;) {
   int n = countNumber(result, i);
   if (n == 2) {
    count++;
   }
   i += n;
  }

  return count;
 }

 public int addThree(int a, int b) {
  return a * a * a + b * b * b;
 }

 public int countNumber(int[] array, int st) {
  int number = 1;
  int len = array.length;
  for (int i = st + 1; i < len; i++) {
   if (array[i] == array[st]) {
    number++;
   }
  }
  return number;
 }

}