HDU 6216 A Cubic number and A Cubic Number【数学思维+枚举/二分】

#include <iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<map>
#include<set>
#include<string>
using namespace std;

int main()
{
    int t,p,flag;
    scanf("%d",&t);
    while(t--)
    {
        flag=0;
        scanf("%d",&p);
        for(int i=1;i<=1e6+10;i++)
        {
            if(3*i*i+3*i+1==p)
            {
                flag=1;
                break;
            }
        }
        if(flag) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}

#define _CRT_SECURE_NO_WARNINGS  
#include <iostream>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <string.h>  
#include <string>  
#define ll long long  
  
using namespace std;  
  
const int MAXN = 1e6 + 5;  
ll tab[MAXN];  
  
void init()  
{  
    for (ll i = 0;i < MAXN;++i)  
        tab[i] = 3 * i*i + 3 * i + 1;  
}  
  
  
int main()  
{  
    int T;  
    scanf("%d", &T);  
    init();  
    for (int i = 1;i <= T;++i)  
    {  
        bool flag = false;  
        ll v;  
        scanf("%I64d", &v);  
        int left = 0, right = MAXN-1;  
        int mid = (left + right) >> 1;  
        while (left <= right)  
        {  
            if (v == tab[mid])  
            {  
                flag = true;  
                break;  
            }  
            else if (v > tab[mid])  
                left = mid + 1;  
            else  
                right = mid - 1;  
            mid = (left + right) >> 1;  
        }  
        if (flag)  
            printf("YES\n");  
        else  
            printf("NO\n");  
    }  
    //system("pause");  
    return 0;  
}