Codeforces Round #245 (Div. 2) B - Balls Game

暴利搜尋即可

#include <iostream>
#include <vector>
#include <iostream>

using namespace std;

int main(){
    int n,k,x;
    cin >> n >> k >> x;
    vector<int> c(n);
    for(int i = 0 ; i < n; ++ i) cin >> c[i];
    int ans = 0;
    for(int i = 1; i < n ; ++ i){
        if(c[i] == x && c[i] == c[i-1]){
            int left = i-1, right = i,s=0,flag = 1;
            while(true){
                int left_cnt = 0, right_cnt = 0,j,k;
                for(j = left; j >= 0 && c[j] == c[left]; -- j) left_cnt++;
                for(k = right; k < n && c[k] == c[right]; ++ k) right_cnt++;
                if(left_cnt+right_cnt + flag >= 3 && c[left] == c[right]){
                    left = j;right =k;
                    s+=left_cnt+right_cnt;
                    flag = 0;
                 }else{
                    ans = max(ans,s);break;
                }
            }
        }
        
    }
    cout<<ans<<endl;
}