Description#
Given a string str, return parsed JSON parsedStr. You may assume the str is a valid JSON string hence it only includes strings, numbers, arrays, objects, booleans, and null. str will not include invisible characters and escape characters.
Please solve it without using the built-in JSON.parse method.
Example 1:
Input: str = '{"a":2,"b":[1,2,3]}'
Output: {"a":2,"b":[1,2,3]}
Explanation: Returns the object represented by the JSON string.Example 2:
Input: str = 'true'
Output: true
Explanation: Primitive types are valid JSON.
Example 3:
Input: str = '[1,5,"false",{"a":2}]'
Output: [1,5,"false",{"a":2}]
Explanation: Returns the array represented by the JSON string.
Constraints:
str is a valid JSON string1 <= str.length <= 105
Solutions#
Solution 1#
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| function jsonParse(str: string): any {
const n = str.length;
let i = 0;
const parseTrue = (): boolean => {
i += 4;
return true;
};
const parseFalse = (): boolean => {
i += 5;
return false;
};
const parseNull = (): null => {
i += 4;
return null;
};
const parseNumber = (): number => {
let s = '';
while (i < n) {
const c = str[i];
if (c === ',' || c === '}' || c === ']') {
break;
}
s += c;
i++;
}
return Number(s);
};
const parseArray = (): any[] => {
const arr: any[] = [];
i++;
while (i < n) {
const c = str[i];
if (c === ']') {
i++;
break;
}
if (c === ',') {
i++;
continue;
}
const value = parseValue();
arr.push(value);
}
return arr;
};
const parseString = (): string => {
let s = '';
i++;
while (i < n) {
const c = str[i];
if (c === '"') {
i++;
break;
}
if (c === '\\') {
i++;
s += str[i];
} else {
s += c;
}
i++;
}
return s;
};
const parseObject = (): any => {
const obj: any = {};
i++;
while (i < n) {
const c = str[i];
if (c === '}') {
i++;
break;
}
if (c === ',') {
i++;
continue;
}
const key = parseString();
i++;
const value = parseValue();
obj[key] = value;
}
return obj;
};
const parseValue = (): any => {
const c = str[i];
if (c === '{') {
return parseObject();
}
if (c === '[') {
return parseArray();
}
if (c === '"') {
return parseString();
}
if (c === 't') {
return parseTrue();
}
if (c === 'f') {
return parseFalse();
}
if (c === 'n') {
return parseNull();
}
return parseNumber();
};
return parseValue();
}
|
