判断完全立方数——cf比赛总结

	while(l<=r)
		{
			 ll mid = (l+r)/2;
			 if((ll)(mid*mid*mid)<j) l=mid+1;
			 else 
			 {
			 	r=mid-1;
			 	ans=mid;
			 }
		}
		if(ans*ans*ans==j) return true;

例题
ac代码

#include<bits/stdc++.h>

using namespace std;
#define ll long long 
bool check(ll x)
{
	for(ll i=1; i*i*i<=x; i++)
	{
	    ll j =x-i*i*i;
	    //printf("j=%lld\n",j);
	    ll  l=1,r=min(j,10000*1ll);//这里的r不能直接=j，否则可能会爆 
		ll ans=-1;
		if(j<=0) continue;
		while(l<=r)
		{
			 ll mid = (l+r)/2;
			 if((ll)(mid*mid*mid)<j) l=mid+1;
			 else 
			 {
			 	r=mid-1;
			 	ans=mid;
			 }
		}
		if(ans*ans*ans==j) return true;
	}
	return false;
}
int main()
{
	
	int t;
	cin>>t;
	while(t--)
	{
		ll n;
		scanf("%lld",&n);
		if(check(n)) puts("YES");
		else puts("NO");
	}
	
	return 0;
}