51NOD 1087 1 10 100 1000
http://www.51nod.com/onlineJudge/questionCode.html#!problemId=1087
暴力大法
#include<bits/stdc++.h> using namespace std; map <int,int>s; void solve() { int i=1,k=1; while (i<=1e9) { s[i] = 1; i+=k; k++; } } int main () { int t,n; solve();scanf("%d",&t); while (t--){ scanf("%d",&n); printf("%d\n",s[n]); } }
百度 an - an-1 = n-1 就可以知道通项公式
然后 用公式算
#include<bits/stdc++.h> using namespace std; int main () { int t,n; scanf("%d",&t); while (t--){ scanf("%d",&n); int t = sqrt(2*n-2); if(t * (t+1) == 2*n-2) printf("1\n"); else printf("0\n"); } }