[zoj3629]找规律

题意：a[n] = ([n/1] + [n/2] + ... + [n/n]) & 1 == false，找出a数组的规律来就ok了。

 1 #pragma comment(linker, "/STACK:10240000,10240000")
 2
 3 #include <iostream>
 4 #include <cstdio>
 5 #include <algorithm>
 6 #include <cstdlib>
 7 #include <cstring>
 8 #include <map>
 9 #include <queue>
10 #include <deque>
11 #include <cmath>
12 #include <vector>
13 #include <ctime>
14 #include <cctype>
15 #include <set>
16
17 using namespace std;
18
19 #define mem0(a) memset(a, 0, sizeof(a))
20 #define lson l, m, rt << 1
21 #define rson m + 1, r, rt << 1 | 1
22 #define define_m int m = (l + r) >> 1
23 #define rep(a, b) for (int a = 0; a < b; a++)
24 #define rrep(a, b) for (int a = (b - 1); a >= 0; a--)
25 #define all(a) (a).begin(), (a).end()
26 #define lowbit(x) ((x) & (-(x)))
27 #define constructInt4(name, a, b, c, d) name(int a = 0, int b = 0, int c = 0, int d = 0): a(a), b(b), c(c), d(d) {}
28 #define constructInt3(name, a, b, c) name(int a = 0, int b = 0, int c = 0): a(a), b(b), c(c) {}
29 #define constructInt2(name, a, b) name(int a = 0, int b = 0): a(a), b(b) {}
30 #define pc(a) putchar(a)
31 #define ps(a) printf("%s", a)
32 #define pd(a) printf("%d", a)
33 #define sd(a) scanf("%d", &a)
34
35 typedef double db;
36 typedef long long LL;
37 typedef unsigned long long uLL;
38 typedef pair<int, int> pii;
39 typedef multiset<int> msi;
40 typedef set<int> si;
41 typedef vector<int> vi;
42 typedef map<int, int> mii;
43
44 const int dx[8] = {0, 1, 0, -1, 1, 1, -1, -1};
45 const int dy[8] = {1, 0, -1, 0, -1, 1, 1, -1};
46 const int maxn = 5 * 1e4 + 7;
47 const int maxm = 1e5 + 7;
48 const int minv = 1e7 + 7;
49 const int max_val = 1e6 + 7;
50 const int MD = 1e9 +7;
51 const LL INF = 1e15;
52 const double PI = acos(-1.0);
53 const double eps = 1e-10;
54
55 template<class T> T gcd(T a, T b) { return b == 0? a : gcd(b, a % b); }
56
57 uLL a, b;
58
59 uLL g(LL n) { return n * (2 * n - 1); }
60
61 uLL f(uLL x) {
62     uLL l = 1, r = 0xFFFFFFFF;
63     while (l < r) {
64         uLL m = (l + r) >> 1;
65         if (m * m < x) l = m + 1;
66         else r = m;
67     }
68     uLL n = l, rest = x - (n - 1) * (n - 1), ans = 0;
69     if (n & 1) ans += rest;
70     ans += g(n >> 1);
71     return ans;
72 }
73
74 int main() {
75     //freopen("in.txt", "r", stdin);
76     while (cin >> a >> b) {
77         a++; b++;
78         cout << f(b) - f(a - 1) << endl;
79     }
80     return 0;
81 }