华中科大校赛预赛1606 Naive

Naive

Time Limit: 3 Sec   Memory Limit: 128 MB
Submissions: 316   Solved: 36

Description

Give you a positive integer x, determine whether it is the sum of three positive cubic numbers.

Input

There’re several test cases. For each case:
Only one line containing an integer x (1≤x≤10^6)

Output

For each test case, print “Yes” if it is or “No” if it isn’t.
(See sample for more details)

Sample Input

1
3
10

Sample Output

No
Yes
Yes

HINT

Source

Problem Setter : Zhou Zhou

题意：  一个数是否可以表示成3个数的立方和   3个数可以为同一个数

思路 ：

一开始直接暴力 先输入n  再去判断n是不是符合条件   结果超时了

后来换了个思维  先找出符合条件的  再看n在不在  小水题把

#include<stdio.h>
#include<string.h>
int a[105];
bool flag[1000000+10];
int main()
{
	int i,j,k,n,mid;
    for(i=1;i<=100;i++)
		a[i]=i*i*i;
    memset(flag,0,sizeof(flag));
    for(i=1;i<=100;i++)
		for(j=i;j<=100;j++)
			for(k=j;k<=100;k++)
			{
                  mid=a[i]+a[j]+a[k];
				if(mid<=1000000)
			     flag[mid]=1;
			}
	while(scanf("%d",&n)!=EOF)
	{
		if(flag[n]) printf("Yes\n");
		else printf("No\n");
	}
	
	return 0;
}