Codeforces Round #435 (Div. 2) D. Mahmoud and Ehab and the binary string[二分]

 1 #define _CRT_SECURE_NO_DEPRECATE
 2 #pragma comment(linker, "/STACK:102400000,102400000")
 3 #include<iostream>  
 4 #include<cstdio>  
 5 #include<fstream>  
 6 #include<iomanip>
 7 #include<algorithm>  
 8 #include<cmath>  
 9 #include<deque>  
10 #include<vector>
11 #include<bitset>
12 #include<queue>  
13 #include<string>  
14 #include<cstring>  
15 #include<map>  
16 #include<stack>  
17 #include<set>
18 #include<functional>
19 #define pii pair<int, int>
20 #define mod 1000000007
21 #define mp make_pair
22 #define pi acos(-1)
23 #define eps 0.00000001
24 #define mst(a,i) memset(a,i,sizeof(a))
25 #define all(n) n.begin(),n.end()
26 #define lson(x) ((x<<1))  
27 #define rson(x) ((x<<1)|1) 
28 #define inf 0x3f3f3f3f
29 typedef long long ll;
30 typedef unsigned long long ull;
31 using namespace std;
32 const int maxn = 1e3 + 5;
33 
34 string a;
35 int ans0, ans1;
36 int main()
37 {
38     ios::sync_with_stdio(false);
39     cin.tie(0); cout.tie(0);
40     int i, j, k, m, n;
41     cin >> n;
42     int mode;
43     a.append(n, ‘0‘);
44     int cas = 0, test;
45     cout << "? " << a << endl;
46     cout.flush();
47     cin >> cas;
48     a[n - 1] = ‘1‘;
49     cout << "? " << a << endl;
50     cout.flush();
51     cin >> test;
52     if (test == cas + 1) { ans0 = n; mode = 1; }
53     else { ans1 = n; mode = 0; }
54     if (mode == 0) { cas = n - cas; for (int i = 0; i < n; ++i)a[i] = ‘1‘; }
55     else cas = test;
56     int l = 0, r = n - 2;
57     while (r - l > 1)
58     {
59         int mid = l + r >> 1;
60         for (int i = l; i <= mid; ++i)a[i] = mode + ‘0‘;
61         cout << "? " << a << endl;
62         cout.flush();
63         cin >> test;
64         int len = mid - l + 1;
65         if (test - len == cas) { l = mid + 1; cas = test; }
66         else { for (int i = l; i <= mid; ++i)a[i] = (mode ^ 1) + ‘0‘; r = mid; }
67     }
68     a[l] = mode + ‘0‘;
69     cout << "? " << a << endl;
70     cout.flush();
71     cin >> test;
72     if (test == cas - 1)
73     {
74         if (mode == 1)ans1 = l+1;
75         else ans0 = l+1;
76     }
77     else
78     {
79         if (mode == 1)ans1 = r+1;
80         else ans0 = r+1;
81     }
82     cout << "! " << ans0 << " " << ans1 << endl;
83     cout.flush();
84     return 0;
85 }