Just a simple Implementation Problem
Complexity\n- Time complexity : O(N)\n Add your time complexity here, e.g. O(n) \n\n- Space complexity : O(1)\n Add your space complexity here, e.g. O(n) \n\n# 
# Complexity\n- Time complexity : $$O(N)$$\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity : $$O(1)$$\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution {\npublic:\n    string entityParser(string text) {\n        int n = text.size();\n        \n        string ans;\n        int i = 0;\n        while(i < n) {\n            if(i+7 <= n && text.substr(i,7) == "&frasl;") {\n                ans += \'/\';\n                i += 7;\n            }\n\n            else if(i+6 <= n && (text.substr(i,6) == "&quot;" || text.substr(i,6) == "&apos;")) {\n                string s = text.substr(i,6);\n                if(s == "&quot;") {\n                    s.clear();\n                    s += \'"\';\n                }\n                else s = "\'";\n                \n                ans += s;\n                i += 6;\n            }\n\n            else if(i+5 <= n && text.substr(i,5) == "&amp;") {\n                ans += \'&\';\n                i += 5;\n            }\n\n            else if(i+4 <= n && (text.substr(i,4) == "&gt;" || text.substr(i,4) == "&lt;")) {\n                string s = text.substr(i,4);\n                if(s == "&gt;") s = ">";\n                else s = "<";\n                \n                ans += s;\n                i += 4;\n            }\n\n            else {\n                ans += text[i];\n                i++;\n            }\n        }\n        return ans;\n    }\n};\n```
['C++']