严格 O(a) 的暴力都能过,幽默
最慢的点跑了276ms
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int n;
ll a,b;
ll res,cnt;
ll ans;
int f;
int Main()
{
cin>>a>>b;
if(a>b)
swap(a,b);
res=1;
cnt=4;
for(int i=3;i<=a;i++) //严格O(a)
{
res+=cnt;
cnt+=2;
}
ans=res+(b-a-1)*(a-1);
cout<<ans;
return 0;
}
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