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codeforces 1118A一升油a元2生油b元，比较2 * a与b即可#include<bits/stdc++.h>using namespace std;#define fst first#define sec second#define sci(num) scanf("%d",&num)#define scl(num) scanf("%lld",&amp...

求下B进制下的数是奇数还是偶数n=a1∗bK−1+a2n=a_1*b^{K-1} + a_2 n=a1​∗bK−1+a2​nmod  2=((a1mod  2)∗Bmod  2+a2mod &...

求对于a的f(a)=max0<b<agcd(a⊕b,a&b)f(a) = max_{0<b<a}gcd(a \oplus b,a\&b)f(a)=max0<b<a​gcd(a⊕b,a&b)打表找规律对于 a!=2x−1a != 2^x - 1a!=2x−1显然有 f(a) = 2^(x...

看了题解才明白是看差数组变换cici′=ci+1+ci−1−cic_i' = c_{i+1} + c_{i-1} - c_i ci′​=ci+1​+ci−1​−ci​ci+1−ci′=ci−1−cic_{i+1} - c_i' = c_{i-1} - c_ici+1​−ci′​=ci−1​−ci​ci′−ci−1=ci+1−cic_i&#x2...

V + 等差求2-(N-1-V)的和#include<bits/stdc++.h>using namespace std;#define fst first#define sec second#define sci(num) scanf("%d",&num)#define scl(num) scanf("%lld",&num)#define mem(a,b...