81989

Run ID	Author	Problem	Lang	Verdict	Time	Memory	Code Length	Submit Time
81989	sh25_shenpy	求 n 累加和(ja)	C++	Wrong Answer	0 MS	248 KB	125	2026-01-09 18:11:34

#include<bits/stdc++.h> using namespace std; int main() { int n; cin>>n; cout<<(n+1)*n/2; return 0; }