AC了

但是样例没通过

建议加一组hack数据，这数据就是样例

for(int i=0;i<depth;i++){
		plus_depth=false;
		for(int j=0;j<second_search[i];j++){
			if(board_bfs_path[i][j][0]-2>=0 and board_bfs_path[i][j][1]+1<=m-1){
				if(!(board[board_bfs_path[i][j][0]-2][board_bfs_path[i][j][1]+1]+1)){
					board[board_bfs_path[i][j][0]-2][board_bfs_path[i][j][1]+1]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]-2;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]+1;
					second_search[i+1]++;
				}
			}//第一处，上右
			if(board_bfs_path[i][j][0]-1>=0 and board_bfs_path[i][j][1]+2<=m-1){
				if(!(board[board_bfs_path[i][j][0]-1][board_bfs_path[i][j][1]+2]+1)){
					board[board_bfs_path[i][j][0]-1][board_bfs_path[i][j][1]+2]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]-1;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]+2;
					second_search[i+1]++;
				}
			}//第二处，右上
			if(board_bfs_path[i][j][0]+1<=n-1 and board_bfs_path[i][j][1]+2<=m-1){
				if(!(board[board_bfs_path[i][j][0]+1][board_bfs_path[i][j][1]+2]+1)){
					board[board_bfs_path[i][j][0]+1][board_bfs_path[i][j][1]+2]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]+1;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]+2;
					second_search[i+1]++;
				}
			}//第三处，右下
			if(board_bfs_path[i][j][0]+2<=n-1 and board_bfs_path[i][j][1]+1<=m-1){
				if(!(board[board_bfs_path[i][j][0]+2][board_bfs_path[i][j][1]+1]+1)){
					board[board_bfs_path[i][j][0]+2][board_bfs_path[i][j][1]+1]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]+2;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]+1;
					second_search[i+1]++;
				}
			}//第四处，下右
			if(board_bfs_path[i][j][0]+2<=n-1 and board_bfs_path[i][j][1]-1>=0){
				if(!(board[board_bfs_path[i][j][0]+2][board_bfs_path[i][j][1]-1]+1)){
					board[board_bfs_path[i][j][0]+2][board_bfs_path[i][j][1]-1]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]+2;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]-1;
					second_search[i+1]++;
				}
			}//第五处，下左
			if(board_bfs_path[i][j][0]+1<=n-1 and board_bfs_path[i][j][1]-2>=0){
				if(!(board[board_bfs_path[i][j][0]+1][board_bfs_path[i][j][1]-2]+1)){
					board[board_bfs_path[i][j][0]+1][board_bfs_path[i][j][1]-2]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]+1;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]-2;
					second_search[i+1]++;
				}
			}//第六处，左下
			if(board_bfs_path[i][j][0]-1>=0 and board_bfs_path[i][j][1]-2>=0){
				if(!(board[board_bfs_path[i][j][0]-1][board_bfs_path[i][j][1]-2]+1)){
					board[board_bfs_path[i][j][0]-1][board_bfs_path[i][j][1]-2]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]-1;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]-2;
					second_search[i+1]++;
				}
			}//第七处，左上
			if(board_bfs_path[i][j][0]-2>=0 and board_bfs_path[i][j][1]-1>=0){
				if(!(board[board_bfs_path[i][j][0]-2][board_bfs_path[i][j][1]-1]+1)){
					board[board_bfs_path[i][j][0]-2][board_bfs_path[i][j][1]-1]=i+1;
					if(plus_depth==false){
						plus_depth=true;
						depth++;
					}
					board_bfs_path[i+1][second_search[i+1]][0]=board_bfs_path[i][j][0]-2;
					board_bfs_path[i+1][second_search[i+1]][1]=board_bfs_path[i][j][1]-1;
					second_search[i+1]++;
				}
			}//第八处，上左
		}
	}