Perhaps you should try some spelling variations:
"cong tinh doi snippets" » "cong trinh doi snippets", "cong vinh doi snippets", "cong thanh doi snippets", "cong trinh doc snippets", "cong trinh do snippets", "cong tinh hoc snippets"
"dung java java snippets" » "dung va java snippets"
"locating bug code snippets" » "locating bung code snippets", "locating bugs code snippets", "locating bug core snippets"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("cong tinh doi snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("cong tinh doi snippets") OR ("dung java java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( cong tinh doi snippets ) or ( dung java java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("cong tinh doi snippets") or ("dung java java snippets"))) or ("locating bug code snippets"))*.