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| #include <iostream>
#include <vector>
#include <stack>
#include <random>
using namespace std;
#define QueenNumber 8
#define stepVegas 2
int trycol[100];
bool isPositionOpen(int x, int y, vector<int> col, vector<int> diag45, vector<int> diag135)
{
int tem;
for(tem = 0; tem < col.size(); tem++){
if(col[tem] == y)
return false;
}
for(tem = 0; tem < diag45.size(); tem++){
if(diag45[tem] == x-y)
return false;
}
for(tem = 0; tem < diag135.size(); tem++){
if(diag135[tem] == x+y)
return false;
}
return true;
}
void backtrace (int k, vector<int> col, vector<int> diag45, vector<int> diag135, bool &success)
{
stack<int> colStack;
int i = k, j = 1, tem;
bool isOpenFind;
while(i <= QueenNumber){
isOpenFind = false;
while(j <= QueenNumber){
if(isPositionOpen(i, j, col, diag45, diag135)){
isOpenFind = true;
col.push_back(j);
diag45.push_back(i-j);
diag135.push_back(i+j);
break;
}
j++;
}
if(isOpenFind){
colStack.push(j);
i++;
j = 1;
}
else{
if(colStack.empty()){
success = false;
return;
}
j = colStack.top();
colStack.pop();
i--;
for (vector<int>::iterator iter = col.begin(); iter != col.end(); ++iter){
if(*iter == j){
col.erase(iter);
break;
}
}
for (vector<int>::iterator iter = diag45.begin(); iter != diag45.end(); ++iter){
if(*iter == i-j){
diag45.erase(iter);
break;
}
}
for (vector<int>::iterator iter = diag135.begin(); iter != diag135.end(); ++iter){
if(*iter == i+j){
diag135.erase(iter);
break;
}
}
j++;
}
}
success = true;
for(tem=QueenNumber; tem>=k; tem--){
trycol[tem] = colStack.top();
colStack.pop();
}
}
void QueenLV(bool &success)
{
vector<int> col, diag45, diag135;
col.clear();
diag45.clear();
diag135.clear();
int k = 0, nb, i, j;
random_device rd;
mt19937 gen(rd());
do{
nb = 0;
for(i = 1; i <= QueenNumber; i++){
if(isPositionOpen(k+1, i, col, diag45, diag135)){
nb++;
uniform_int_distribution<> dis(1, nb);
if(dis(gen) == 1){
j = i;
}
}
}
if(nb > 0){
k++;
trycol[k] = j;
col.push_back(j);
diag45.push_back(k-j);
diag135.push_back(k+j);
}
}while(nb !=0 && k != stepVegas);
if(nb == 0){
success = false;
}
else{
backtrace(stepVegas+1, col, diag45, diag135, success);
}
}
int main()
{
bool success;
do{
QueenLV(success);
}while(!success);
if(success){
for(int i=1; i<= QueenNumber; i++){
cout<<trycol[i]<<endl;
}
}
else{
cout<<"hello world!\n"<<endl;
}
getchar();
return 0;
}
|
