110 lines
2.2 KiB
C++
110 lines
2.2 KiB
C++
#include <string>
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#include <cstdlib>
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#include <utility>
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using std::string;
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typedef unsigned long long count_type;
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class line;
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typedef std::pair<line*, line*> two_lines;
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// Treap node representation of a line
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struct line {
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count_type priority, size;
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string text;
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line *left, *right;
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line(count_type _p, string _t) : priority(_p), text(_t), size(1), left(nullptr), right(nullptr) {}
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};
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// Treap representation of a file
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class file {
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public:
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line* root;
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// Get size uf a subtreap
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int get_size(line* l) {
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if(l == nullptr) return 0;
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return l->size;
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}
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// Split treap by k-th element
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// Hopefully with sizes
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two_lines split(line *l, count_type k) {
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if(l == nullptr) return {nullptr, nullptr};
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if(get_size(l->left) > k) {
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// In the left subtree
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auto two = split(l->left, k);
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l->size -= get_size(two.first);
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return {two.first, l};
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}
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else {
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// In the right subtree
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auto two = split(l->right, k - (1+get_size(l->left)));
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l->size -= get_size(two.second);
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return {l, two.second};
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}
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}
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// Join two treaps
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// Hopefully with working sizes
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line* join(line *a, line *b) {
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if(a == nullptr) return b;
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if(b == nullptr) return a;
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if(a->priority < b->priority) {
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a->size += b->size;
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a->right = join(a->right, b);
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return a;
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}
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else {
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b->size += a->size;
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b->left = join(a, b->left);
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return b;
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}
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}
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line* join(two_lines two) { return join(two.first, two.second); }
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// Find k-th line of file
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line* find(line* l, count_type k) {
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if(l == nullptr) return nullptr;
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if(k <= get_size(l->left))
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return find(l->left, k);
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else if(k == get_size(l->left)+1)
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return l;
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else
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return find(l->right, k - (1+get_size(l->left)) );
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}
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public:
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file() {
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srand(120);
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root = nullptr;
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}
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// File access
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// Don't find index k, but k-th line -> +1
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line* find(count_type k) {
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if(k >= root->size)
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return nullptr;
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return find(root, k+1);
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}
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// Line insert
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void insert(int k, string s) {
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line *l = new line(rand(), s);
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if(root == nullptr) {
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root = l;
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return;
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}
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auto two = split(root, k);
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two.first = join(two.first, l);
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join(two);
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}
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// Line removal
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void remove(count_type k) {
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auto two = split(root, k);
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two.first = split(two.first, k-1).first;
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join(two);
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}
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};
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