裸干usaco prime3

[手动搬家自网易博客 原发表日期：2009-07-24 15:13]

  刚在网上查了一下usaco prime3，发现还是有不少优化，可惜我都没用，只是写了一个比较暴力的数据结构（好像叫字典树？）+明显的剪枝。程序写了320行（包括一些debug用的东西），汗……

无辜的代码飘过：

/* * $File: prime3.cpp * $Date: Fri Jul 24 14:58:57 2009ID: gy_jk2LANG: C++TASK: prime3 */#define INPUT"prime3.in"#define OUTPUT"prime3.out"//#define DEBUG 1#ifdef DEBUG#include <iostream>using namespace std;#endif#include <cstdio>#include <cassert>#include <cstring>namespace Solve{struct Tree_node{int val;Tree_node *child, *brother, *parent;Tree_node(int v, Tree_node *b = NULL, Tree_node *p = NULL) : val(v), child(NULL), brother(b), parent(p) {}~Tree_node() {if (child != NULL) delete child; if (brother != NULL) delete brother;}};Tree_node *prime_tree;void insert_into_tree(int num, int rest_depth, Tree_node *root);// insert @num into @root in !reverse! order (e.g, 123 -> 321)Tree_node* find_in_cur_level(int num, Tree_node *root);// return NULL if nothing found.#ifdef DEBUGvoid print_tree(Tree_node *root, int n){if (root->child == NULL)cout << n << endl;for (Tree_node *ptr = root->child; ptr != NULL; ptr = ptr->brother)print_tree(ptr, n * 10 + ptr->val);}#endifconst int PRIME_RANGE_BEGIN = 10000, PRIME_RANGE_END = PRIME_RANGE_BEGIN * 10;void init_prime(int sum);int square[5][5];Tree_node *root_row[5], *root_diagonal[2];int digit_usable[5][5];void dfs(int row, int col, Tree_node *root);const char *NO_ANSWER = "NONE/n";struct Answer{int square[5][5];Answer *next;Answer(Answer *n) : next(n) {memcpy(this->square, Solve::square, sizeof(Solve::square));}bool operator < (const Answer &n);};Answer *answer, **answer_array;int nanswer;void solve(FILE *fin, FILE *fout);}void Solve::solve(FILE *fin, FILE *fout){int n0, sum;assert(fscanf(fin, "%d %d", ∑, &n0) == 2);init_prime(sum);#ifdef DEBUGprint_tree(prime_tree, 0);#endiffor (int i = 0; i < 5; i ++){for (int j = 0; j < 5; j ++)if (i == 0 && j == 0)digit_usable[i][j] = 1 << n0;else digit_usable[i][j] = 0xFFF;root_row[i] = prime_tree;}root_diagonal[0] = root_diagonal[1] = prime_tree;dfs(0, 0, prime_tree);if (answer != NULL){answer_array = new Answer*[nanswer];int pos = 0;for (Answer *ptr = answer; ptr != NULL; ptr = ptr->next)answer_array[pos ++] = ptr;for (int i = 1; i < nanswer; i ++){Answer *key = answer_array[i];pos = i - 1;while (pos >= 0 && (*key) < (*answer_array[pos])){answer_array[pos + 1] = answer_array[pos];pos --;}answer_array[pos + 1] = key;}for (int i = 0; i < nanswer; i ++){if (i)fprintf(fout, "/n");for (int x = 0; x < 5; x ++){for (int y = 0; y < 5; y ++)fprintf(fout, "%d", answer_array[i]->square[x][y]);fprintf(fout, "/n");}delete answer_array[i];}delete []answer_array;} else fprintf(fout, "%s", NO_ANSWER);delete prime_tree;}bool Solve::Answer::operator < (const Answer &n){for (int i = 0; i < 5; i ++)for (int j = 0; j < 5; j ++)if (square[i][j] < n.square[i][j])return true;else if (square[i][j] > n.square[i][j])return false;return false;}Solve::Tree_node* Solve::find_in_cur_level(int num, Tree_node *root){if (root == NULL)return NULL;Tree_node *pos = root->child;while (pos != NULL && pos->val < num)pos = pos->brother;if (pos == NULL || pos->val > num)return NULL;return pos;}void Solve::dfs(int row, int col, Tree_node *root){if (row == 5){row = 0;col ++;if (col == 5){answer = new Answer(answer);nanswer ++;return;}root = prime_tree;}if (col == 4){int du = digit_usable[row][col];int &sq = square[row][col];for (Tree_node *ptr = root->child; ptr != NULL; ptr = ptr->brother)if (du & (1 << ptr->val)){sq = ptr->val;dfs(row + 1, col, ptr);}return;}int du = digit_usable[row][col];int &sq = square[row][col];bool d0 = (row == col), d1 = (row + col == 4);int u0 = digit_usable[row][col + 1], u1 = 0, u2 = 0;if (d0)u1 = digit_usable[row + 1][col + 1];if (d1)u2 = digit_usable[row - 1][col + 1];for (Tree_node *ptr = root->child; ptr != NULL; ptr = ptr->brother)if (du & (1 << ptr->val)){Tree_node *r0 = find_in_cur_level(sq = ptr->val, root_row[row]), *r1 = NULL, *r2 = NULL;if (r0 == NULL)continue;if (d0){if ((r1 = find_in_cur_level(ptr->val, root_diagonal[0])) == NULL)continue;}if (d1){if ((r2 = find_in_cur_level(ptr->val, root_diagonal[1])) == NULL)continue;}root_row[row] = r0;int mask = 0;for (Tree_node *p = r0->child; p != NULL; p = p->brother)mask |= 1 << p->val;if ((digit_usable[row][col + 1] = u0 & mask) == 0){root_row[row] = r0->parent;continue;}if (d0){root_diagonal[0] = r1;mask = 0;for (Tree_node *p = r1->child; p != NULL; p = p->brother)mask |= 1 << p->val;if ((digit_usable[row + 1][col + 1] = u1 & mask) == 0){root_row[row] = r0->parent;root_diagonal[0] = r1->parent;continue;}}if (d1){root_diagonal[1] = r2;mask = 0;for (Tree_node *p = r2->child; p != NULL; p = p->brother)mask |= 1 << p->val;if ((digit_usable[row - 1][col + 1] = u2 & mask) == 0){root_row[row] = r0->parent;if (d0)root_diagonal[0] = r1->parent;root_diagonal[1] = r2->parent;continue;}}dfs(row + 1, col, ptr);root_row[row] = r0->parent;if (d0)root_diagonal[0] = r1->parent;if (d1)root_diagonal[1] = r2->parent;}digit_usable[row][col + 1] = u0;if (d0)digit_usable[row + 1][col + 1] = u1;if (d1)digit_usable[row - 1][col + 1] = u2;}void Solve::insert_into_tree(int num, int rest_depth, Tree_node *root){if (rest_depth == 0)return;Tree_node *pos = root->child, *last = NULL;int digit = num % 10;while (pos != NULL && pos->val < digit){last = pos;pos = pos->brother;}if (pos != NULL && pos->val == digit)insert_into_tree(num / 10, rest_depth - 1, pos);else if (last == NULL)insert_into_tree(num / 10, rest_depth - 1, root->child = new Tree_node(digit, root->child, root));else insert_into_tree(num / 10, rest_depth - 1, last->brother = new Tree_node(digit, pos, root));}void Solve::init_prime(int sum){unsigned int tmp[PRIME_RANGE_END / 32 + 1] = {0};prime_tree = new Tree_node(-1);#ifdef DEBUGconst int P[] = {11351, 14033, 30323, 53201, 13313, 14303, 13331};for (int i = 0; i < 7; i ++){int n1 = 0;for (int j = P[i]; j; j /= 10)n1 = n1 * 10 + (j % 10);insert_into_tree(n1, 5, prime_tree);}return;#endif#define VISIT(_p_) (tmp[(_p_) >> 5] & (1 << ((_p_) & 31)))#define SET(_p_) tmp[(_p_) >> 5] |= (1 << ((_p_) & 31))for (int i = 2; i < PRIME_RANGE_END; i ++)if (VISIT(i) == 0){if (i >= PRIME_RANGE_BEGIN){int s = 0, n1 = 0;for (int j = i; j; j /= 10){s += j % 10;n1 = n1 * 10 + (j % 10);}if (s == sum)insert_into_tree(n1, 5, prime_tree);}for (int j = i * 2; j < PRIME_RANGE_END; j += i)SET(j);}#undef VISIT#undef SET}int main(){FILE *fin = fopen(INPUT, "r"), *fout = fopen(OUTPUT, "w");Solve::solve(fin, fout);fclose(fin);fclose(fout);}