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Nqueens.cpp
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Nqueens.cpp
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#include <iostream>
#include <vector>
#include <cstdlib>
using namespace std;
class Board {
public:
int size;
int* q;
int* c;
int* d1;
int* d2;
Board(int size) {
this->size = size;
this->q = new int[size];
this->c = new int[size];
for (int i = 0; i < size; i++) {
this->c[i] = 0;
}
this->d1 = new int[2 * size - 1];
for (int i = 0; i < 2 * size - 1; i++) {
this->d1[i] = 0;
}
this->d2 = new int[2 * size - 1];
for (int i = 0; i < 2 * size - 1; i++) {
this->d2[i] = 0;
}
for (int i = 0; i < size / 2; i++) {
int col = 2 * i + 1;
this->q[i] = col;
this->c[col]++;
this->d1[col - i + this->size - 1] ++;
this->d2[i + col] ++;
}
int br = 0;
for (int i = size / 2; i < size; i++) {
int col = 2 * br;
br++;
this->q[i] = col;
this->c[col]++;
this->d1[col - i + this->size - 1] ++;
this->d2[i + col] ++;
}
}
void print() {
for (int i = 0; i < this->size; i++) {
for (int j = 0; j < this->size; j++) {
if (j == this->q[i]) {
cout << "*";
}
else {
cout << "-";
}
}
cout << endl;
}
cout << endl;
}
int mostContLine() {
int most = 0;
int current = 0;
int* max = new int[this->size];
int br = 0;
for (int i = 0; i < this->size; i++) {
current += this->c[this->q[i]] - 1;
current += this->d1[this->q[i] - i + this->size - 1] - 1;
current += this->d2[i + this->q[i]] - 1;
if (current > most) {
most = current;
br = 0;
max[br] = i;
}
else if (current == most) {
br++;
max[br] = i;
}
current = 0;
}
int random = rand() % ++br;
return max[random];
}
int LeastContCol(int line) {
int least = 100000;
int current = 0;
this->c[q[line]] --;
this->d1[q[line] - line + this->size - 1] --;
this->d2[line + q[line]] --;
int* min = new int[this->size];
int br = 0;
for (int i = 0; i < this->size; i++) {
current += this->c[i];
current += this->d1[i - line + this->size - 1];
current += this->d2[line + i];
if (current < least) {
least = current;
br = 0;
min[br] = i;
}
else if (current == least) {
br++;
min[br] = i;
}
current = 0;
}
int random = rand() % ++br;
return min[random];
}
bool place(int line, int col) {
this->q[line] = col;
this->c[col] ++;
this->d1[col - line + this->size - 1] ++;
this->d2[line + col] ++;
int current = 0;
for (int i = 0; i < this->size; i++) {
current += this->c[this->q[i]] - 1;
current += this->d1[this->q[i] - i + this->size - 1] - 1;
current += this->d2[i + this->q[i]] - 1;
if (current > 0) {
return false;
}
}
return true;
}
};
void findPlace(Board queens) {
while (true) {
int line = queens.mostContLine();
int col = queens.LeastContCol(line);
if (queens.place(line, col))
break;
}
queens.print();
return;
}
int main()
{
int size;
cin >> size;
Board queens(size);
findPlace(queens);
return 0;
}