题解 | 小红的三带一

#include<bits/stdc++.h>
using namespace std;
const int N = 2e5 + 9;
int n,a[N],ans,t;
bool ok(int i){
    vector<int>v{a[i], a[i+1], a[i+2], a[i+3]};
    sort(v.begin(),v.end());  //排序
    return(v[0] == v[1] && v[1] == v[2] && v[2] != v[3])||
          (v[0] != v[1] && v[1] == v[2] && v[2] == v[3]);
}
void solve(){
    cin>>n;
    for(int i = 0 ; i < n ; i ++) cin>>a[i];
    int ans = 0;
    for(int i = 0; i + 3 < n ;){
        if(ok(i)){
            ans++;
            i += 4;  //有的话就跳过这些
        }
        else i++;  //没得话继续
    }
    cout<<ans;
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int o = 1;
    //cin>>o;
    while(o--){
        solve();
    }
    return 0;
}