mirror of
https://git.sb/baoshuo/OI-codes.git
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139 lines
2.6 KiB
C++
139 lines
2.6 KiB
C++
#include <iostream>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 35005,
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K = 55;
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template <typename T>
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class SegmentTree {
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private:
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struct node {
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int l, r;
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T m, d;
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node *lchild, *rchild;
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node(int _l = 0, int _r = 0)
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: l(_l),
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r(_r),
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m(0),
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d(0),
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lchild(nullptr),
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rchild(nullptr) {}
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~node() {
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delete lchild;
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delete rchild;
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}
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void pushup() {
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m = 0;
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if (lchild) m = std::max(m, lchild->m);
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if (rchild) m = std::max(m, rchild->m);
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}
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void pushdown() {
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if (!d) return;
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lchild->d += d;
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rchild->d += d;
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lchild->m += d;
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rchild->m += d;
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d = 0;
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}
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};
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void build(node *&u, int l, int r) {
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u = new node(l, r);
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if (l == r) return;
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int mid = l + r >> 1;
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build(u->lchild, l, mid);
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build(u->rchild, mid + 1, r);
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}
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void modify(node *u, int l, int r, T v) {
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if (l <= u->l && u->r <= r) {
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u->d += v;
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u->m += v;
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return;
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}
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u->pushdown();
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int mid = u->l + u->r >> 1;
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if (l <= mid) modify(u->lchild, l, r, v);
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if (r > mid) modify(u->rchild, l, r, v);
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u->pushup();
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}
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T query(node *u, int l, int r) {
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if (l <= u->l && u->r <= r) return u->m;
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u->pushdown();
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int mid = u->l + u->r >> 1;
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T res = 0;
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if (l <= mid) res = std::max(res, query(u->lchild, l, r));
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if (r > mid) res = std::max(res, query(u->rchild, l, r));
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return res;
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}
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node *root;
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public:
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SegmentTree(int n)
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: root(nullptr) {
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build(root, 1, n);
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}
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void modify(int l, int r, T v) {
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modify(root, l, r, v);
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}
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T query(int l, int r) {
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return query(root, l, r);
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}
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};
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int n, k, a[N], pre[N], pos[N], f[K][N];
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n >> k;
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for (int i = 1; i <= n; i++) {
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cin >> a[i];
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pre[i] = pos[a[i]];
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pos[a[i]] = i;
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}
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for (int i = 1; i <= k; i++) {
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SegmentTree<int> tr(n);
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for (int j = 1; j <= n; j++) {
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tr.modify(j, j, f[i - 1][j - 1]);
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}
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for (int j = 1; j <= n; j++) {
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tr.modify(pre[j] + 1, j, 1);
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f[i][j] = tr.query(i, j);
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}
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}
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cout << f[k][n] << endl;
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return 0;
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}
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