循环无限运行C++解决骑士之旅问题

我正在用C++编写Knight Tour问题。但它正在无限期地运行。我检查了我的逻辑，与这里提到的逻辑相似

#include<bits/stdc++.h>
using namespace std;
bool isvalid(vector<vector<int>>board,int i,int j)
{
return i >= 0 && j >= 0 && i < 8 && j < 8 ;
};
bool checkcompletion(vector<vector<int>>board)
{
for(int i=0;i<8;i++)
{
for(int j=0;j<8;j++)
if(board[i][j]==0)
return false;
}
return true;
}
int tour(vector<vector<int>>board,int i,int j,int steps)
{
//CHECK IF IT IS A VALID STEP IF NOT VALID THEN RETURN 0
if(!isvalid(board,i,j))
{
return 0;
}
//CHECK IF THAT PLACE IS ALREADY VISITED(MOVED OUT OF ISVALID AS THAT FUNCTION ME 
//GET A OUT OF BOUND REQUEST WHICH WILL CAUSE SEGMENTATION FAULT)
// cout<<i<<" "<<j<<endl;
if(board[i][j]!=0) return 0;
//CHECK IF ALL ARE MARKED FOR TERMINATION
if(steps==64)return 1;
//if(checkcompletion(board)) return 1;

//BACKTRACKING IDEA VARIABLE
board[i][j]=++steps;
for(int i=0;i<8;i++)
{
for(int j=0;j<8;j++)
{
if(board[i][j]>9)
cout<<" "<<board[i][j]<<" ";
else
cout<<" "<<board[i][j]<<"  ";
} 
cout<<"n";
}
cout<<"================================n";
tour(board,i+2,j+1,steps);
tour(board,i+1,j+2,steps);
tour(board,i-1,j+2,steps);
tour(board,i-2,j+1,steps);
tour(board,i-2,j-1,steps);
tour(board,i-1,j-2,steps);
tour(board,i+1,j-2,steps);
tour(board,i+2,j-1,steps);


board[i][j]=0;
}
int main()
{
//for marking the visited part as well as noting the number os steps
vector<vector<int>>board (8,vector<int>(8,0));
int steps = 0;
//MADE steps =1 for 0,0
//board[0][0]=++steps;
//initil position 0,0
tour(board,0,0,steps);
}

有人能告诉我这个代码出了什么问题吗？当我检查数组的中间状态时，它运行得很好。是因为算法很复杂，因此运行时间更长，而我把它误认为是一个无限循环吗？我检查了这个答案，它描述了这个问题有多复杂