排名和队号一样
定义一个完全无向图 G = ( V , E ) G=(V,E) G=(V,E)的边权 W i , j = l c m ( i + 1 , j + 1 ) W_{i,j}=lcm(i+1,j+1) Wi,j=lcm(i+1,j+1),问你当 ∣ V ∣ = n |V|=n ∣V∣=n该图的最小生成树权值模上 k k k为多少
1 ≤ n ≤ 1 0 10 1 \leq n \leq 10^{10} 1≤n≤1010, 1 0 8 ≤ k ≤ 1 0 9 10^{8} \leq k \leq 10^{9} 108≤k≤109
首先考虑如何在该图中找到一个最小生成树,经过模拟,我们很快可以发现只需将所有 i + 1 i+1 i+1为质数的节点挑出来作为一颗子树的根节点,然后将所有此类节点(除 2 2 2以外)与 2 2 2相连,则可以满足题目要求(证明略,可以想象如果更换一条边必然会产生更大的权值),此时该树的权值为:
W = ∑ i = 3 n + 1 i + ∑ i = 3 , i i s p r i m e n + 1 i W=\sum_{i=3}^{n+1}i+\sum_{i=3, i\ is\ prime}^{n+1}i W=i=3∑n+1i+i=3,i is prime∑n+1i
于是我们只需要求出 n + 1 n+1 n+1以内的质数和即可,由于 n n n很大,所以 O ( n ) O(n) O(n)以上的质数筛法显然超时,这是我们需要用到一个叫做 M i n 25 Min25 Min25筛的东西,用于求出任意正整数以内的质数和
另外要注意前一项用等差数列求和时要先判断奇偶,否则会导致溢出
#include
using namespace std;
typedef long long ll;
const int N = 1000010;
struct Min25 {
ll prime[N], id1[N], id2[N], flag[N], ncnt, m;
ll g[N], sum[N], a[N], T, n;
inline int ID(ll x) {
return x <= T ? id1[x] : id2[n / x];
}
inline ll calc(ll x) {
return x * (x + 1) / 2 - 1;
}
inline ll f(ll x) {
return x;
}
inline void Init() {
memset(prime, 0, sizeof(prime));
memset(id1, 0, sizeof(id1));
memset(id2, 0, sizeof(id2));
memset(flag, 0, sizeof(flag));
memset(g, 0, sizeof(g));
memset(sum, 0, sizeof(sum));
memset(a, 0, sizeof(a));
ncnt = m = T = n = 0;
}
inline void init() {
T = sqrt(n + 0.5);
for (int i = 2; i <= T; i++) {
if (!flag[i]) prime[++ncnt] = i, sum[ncnt] = sum[ncnt - 1] + i;
for (int j = 1; j <= ncnt && i * prime[j] <= T; j++) {
flag[i * prime[j]] = 1;
if (i % prime[j] == 0) break;
}
}
for (ll l = 1; l <= n; l = n / (n / l) + 1) {
a[++m] = n / l;
if (a[m] <= T) id1[a[m]] = m; else id2[n / a[m]] = m;
g[m] = calc(a[m]);
}
for (int i = 1; i <= ncnt; i++)
for (int j = 1; j <= m && (ll)prime[i] * prime[i] <= a[j]; j++)
g[j] = g[j] - (ll)prime[i] * (g[ID(a[j] / prime[i])] - sum[i - 1]);
}
inline ll solve(ll x) {
if (x <= 1) return x;
return n = x, init(), g[ID(n)];
}
}a;
int main() {
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int T;
cin >> T;
while (T--) {
ll n, k;
cin >> n >> k;
a.Init();
ll sum = 0;
if (n >= 3) {
if ((n + 4) & 1) sum = (n - 1) / 2 % k * ((n + 4) % k) % k;
else sum = (n + 4) / 2 % k * ((n - 1) % k) % k;
}
sum = (sum + a.solve(n + 1) % k) % k;
cout << (sum + k - 2) % k << '\n';
}
return 0;
}
一共有 n n n个柜子,有 m m m件快递分别放在不同的柜子中,每个柜子之间的距离为 1 1 1,你开始时处于 1 1 1号柜子处,每次拿快递时,你需要首先到 k k k号柜子处输入指令,然后去往与输入指令对应的柜子处取快递,取完最后一件快递后你需要回到 1 1 1号柜子处,问你取完所有快递的最短路径是多少
1 ≤ k ≤ n ≤ 1 0 9 1\leq k \leq n \leq 10^{9} 1≤k≤n≤109
1 ≤ m < m i n ( n , 1 0 9 ) 1 \leq m < min(n, 10^{9}) 1≤m<min(n,109)
∑ m ≤ 2 × 1 0 6 \sum m \leq 2 \times 10^{6} ∑m≤2×106
设 a i a_{i} ai为第 i i i件快递的所在柜子编号, a j a_{j} aj表示最后一次取出的快递柜子编号,则有:
D = ( k − 1 ) + 2 × ∑ i = 1 , i ≠ j m ∣ a i − k ∣ + ∣ a j − k ∣ + a j − 1 D = (k - 1) + 2 \times \sum_{i=1,i\neq j}^{m}|a_{i}-k|+|a_{j}-k|+a_{j}-1 D=(k−1)+2×i=1,i=j∑m∣ai−k∣+∣aj−k∣+aj−1
那么我们只需要枚举 a j a_{j} aj的值即可,时间复杂度 O ( n ) O(n) O(n)
#include
#include
#include
using namespace std;
typedef long long ll;
const int N = 1e6 + 5;
ll a[N];
int main()
{
int T;
scanf("%d", &T);
while (T--)
{
ll n, m, k;
ll sum = 0;
scanf("%lld %lld %lld", &n, &m, &k);
for (int i = 1; i <= m; ++i)
{
scanf("%lld", &a[i]);
ll x = a[i] - k;
if (x < 0) x = -x;
sum += x;
}
ll ans = LLONG_MAX;
for (int i = 1; i <= m; ++i)
{
ll x = a[i] - k;
if (x < 0) x = -x;
ans = min(ans, k - 1 + 2 * sum + a[i] - 1 - x);
}
printf("%lld\n", ans);
}
return 0;
}
花里胡哨,就不解释了
观察样例发现答案为字符串中出现次数最多的字符的个数
#include
using namespace std;
const int maxn = 1e5 + 10;
int main() {
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int T, cnt = 0;
cin >> T;
while (T--) {
string s;
cin >> s;
int a[26] = { 0 };
int len = s.length(), Max = 0;
for (int i = 0; i < len; ++i) {
++a[s[i] - 'a'];
Max = max(Max, a[s[i] - 'a']);
}
cout << "Case " << "#" << ++cnt << ": " << Max << '\n';
}
return 0;
}
给定一个数组,问你是否有相邻的两个 0 0 0或相邻的两个 1 1 1
签到题,直接模拟即可
#include
using namespace std;
int a[66];
int main() {
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int T;
cin >> T;
while (T--) {
int n;
cin >> n;
for (int i = 1; i <= n; ++i) cin >> a[i];
bool tag = false;;
for (int i = 2; i <= n; ++i) {
if (a[i] == a[i - 1]) {
tag = true;
break;
}
}
if (tag) cout << "NO" << '\n';
else cout << "YES" << '\n';
}
return 0;
}
有一个 n × n n \times n n×n的矩阵 A A A和一个 3 × 3 3 \times 3 3×3的矩阵 K K K,现做如下定义
现在给出矩阵 A A A和矩阵 K ′ K' K′,问你 l i m t → ∞ C t ( A , K ) lim_{t \to \infty}C^{t}(A,K) limt→∞Ct(A,K)是多少
3 ≤ n ≤ 50 3 \leq n \leq 50 3≤n≤50
0 ≤ A i , j ≤ 1000 0 \leq A_{i,j} \leq 1000 0≤Ai,j≤1000
0 ≤ K i , j ′ ≤ 1000 0 \leq K'_{i,j} \leq 1000 0≤Ki,j′≤1000
∑ x = 1 3 ∑ y = 1 3 K x , y ′ > 0 \sum_{x=1}^{3}\sum_{y=1}^{3}K'_{x,y} > 0 ∑x=13∑y=13Kx,y′>0
根据定义可知 K i , j ≤ 1 K_{i,j} \leq 1 Ki,j≤1,那么当 K K K矩阵中存在两个及以上不为 0 0 0的数时答案为 0 0 0
当有且仅有一个不为 0 0 0的元素时,考虑当 K 1 , 1 ≠ 0 K_{1,1}\neq 0 K1,1=0,那么显然答案为原 A A A矩阵,否则模拟发现其答案依然为 0 0 0
这题需要注意行末空格问题,不然会 P E PE PE
#include
#include
#include
using namespace std;
typedef long long ll;
int a[55][55];
int k1[3][3];
int main()
{
int T;
scanf("%d", &T);
while (T--)
{
int n;
scanf("%d", &n);
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= n; ++j)
scanf("%d", &a[i][j]);
int sum = 0;
for(int i= 1; i <= 3; ++ i)
for (int j = 1; j <= 3; ++j)
{
scanf("%d", &k1[i][j]);
sum += k1[i][j];
}
if (sum == k1[1][1])
{
for (int i = 1; i <= n; ++i)
{
for (int j = 1; j <= n; ++j)
printf("%d%c",a[i][j], j == n ? '\n':' ');
}
}
else
{
for (int i = 1; i <= n; ++i)
{
for (int j = 1; j <= n; ++j)
printf("0%c", j == n ? '\n' : ' ');
}
}
}
return 0;
}