UVa1607 poj1435 UVaLive1686 Gates

填坑系列(p.246)

由函数连续性得满足二分性

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<cstdlib>
 4 #include<algorithm>
 5 #include<iostream>
 6 
 7 using namespace std;
 8 
 9 void setIO(const string& s) {
10     freopen((s + ".in").c_str(), "r", stdin);
11     freopen((s + ".out").c_str(), "w", stdout);
12 }
13 template<typename Q> Q read(Q& x) {
14     static char c, f;
15     for(f = 0; c = getchar(), !isdigit(c); ) if(c == '-') f = 1;
16     for(x = 0; isdigit(c); c = getchar()) x = x * 10 + c - '0';
17     if(f) x = -x;
18     return x;
19 }
20 template<typename Q> Q read() {
21     static Q x; read(x); return x;
22 }
23 
24 const int N = 200000 + 5;
25 
26 int n, m;
27 struct Gates {
28     int a, b, o;
29 }gates[N];
30 
31 int output(int k) {
32     for(int i = 1; i <= m; i++) {
33         int a = gates[i].a;
34         int b = gates[i].b;
35         int va = a < 0 ? -a > k : gates[a].o;
36         int vb = b < 0 ? -b > k : gates[b].o;
37         gates[i].o = !(va && vb);
38     }
39     return gates[m].o;
40 }
41 
42 int solve(int vn) {
43     int L = 1, R = n;
44     while(L < R) {
45         int mid = L + (R - L) / 2;
46         if(output(mid) == vn) R = mid; else L = mid + 1;
47     }
48     return L;
49 }
50 
51 int main() {
52 #ifdef DEBUG
53     freopen("in.txt", "r", stdin);
54     freopen("out.txt", "w", stdout);
55 #endif
56     
57     int T; scanf("%d", &T);
58     while(T--) {
59         scanf("%d%d", &n, &m);
60         for(int i = 1; i <= m; i++) {
61             scanf("%d%d", &gates[i].a, &gates[i].b);
62         }
63         int v0 = output(0), vn = output(n);
64         if(v0 == vn) for(int i = 1; i <= n; i++) putchar('0');
65         else {
66             int p = solve(vn);
67             for(int i = 1; i < p; i++) putchar('0');
68             putchar('x');
69             for(int i = p + 1; i <= n; i++) putchar('1');
70         }
71         puts("");
72     }
73             
74     
75     return 0;
76 }