1 条题解

  • 1
    @ 2025-6-12 16:15:25
    #include <bits/stdc++.h>
    using namespace std;
    #define ls u << 1
    #define rs u << 1 | 1
    #define LL long long
    #define int long long
    #define PII pair <int, int>
    #define fi first
    #define se second
    #define pub push_back
    #define pob pop_back
    #define puf push_front
    #define pof pop_front
    #define lb lower_bound
    #define ub upper_bound
    #define i128 __int128
    #define pcnt(x) __builtin_popcount(x)
    #define mem(a,goal) memset(a, (goal), sizeof(a))
    #define rep(x,start,end) for(int x = (start) - ((start) > (end)); x != (end) - ((start) > (end)); ((start) < (end) ? x ++ : x --))
    #define aLL(x) (x).begin(), (x).end()
    #define sz(x) (int)(x).size()
    const int INF = 998244353;
    const int mod = 1e9 + 7;
    const int N = 100010;
    void solve()
    {
        int n;
        cin >> n;
        string s;
        cin >> s;
        int cnt0 = 0, cnt1 = 0;
        int ans = 0;
        s = " " + s;
        for(int i = 1; i <= n; ++ i)
        {
            if(s[i] == '0' || s[i] == '?')
            {
                cnt0 ++;
                ans += cnt1;
            }
            else cnt1 ++;
        }
        int res = ans;
        cnt0 = n - cnt1;
        cnt1 = 0;
        for(int i = 1; i <= n; ++ i)
        {
            if(s[i] == '1') cnt1 ++;
            if(s[i] == '0') cnt0 --;
            if(s[i] == '?')
            {
                cnt0 --;
                ans = res - cnt1 + cnt0;
                res = max(res, ans);
                cnt1 ++;
            }
          /*
              if(s[i] == '?')
            {
                cnt0 --;
                ans = res - cnt1 + cnt0;
                cnt1 ++;
                if(ans > res) res = ans;
                else
                {
                    cnt0 ++;
                    cnt1 --;
                }
            }
          */
        }
        cout << res << '\n';
    }
    signed main()
    {
        int t = 1;
        cin >> t;
        while (t --) solve();
        return 0;
    }
    
    • 1

    信息

    ID
    5609
    时间
    1000ms
    内存
    256MiB
    难度
    10
    标签
    (无)
    递交数
    2
    已通过
    1
    上传者