Last updated on January 5th, 2025 at 01:20 am
Here, we see a Solve the Equation LeetCode Solution. This Leetcode problem is solved using different approaches in many programming languages, such as C++, Java, JavaScript, Python, etc.
List of all LeetCode Solution
Topics
Math
Companies
Amazon
Level of Question
Medium
Solve the Equation LeetCode Solution
Table of Contents
1. Problem Statement
Solve a given equation and return the value of 'x' in the form of a string "x=#value". The equation contains only '+', '-' operation, the variable 'x' and its coefficient. You should return "No solution" if there is no solution for the equation, or "Infinite solutions" if there are infinite solutions for the equation.
If there is exactly one solution for the equation, we ensure that the value of 'x' is an integer.
Example 1:
Input: equation = “x+5-3+x=6+x-2”
Output: “x=2”
Example 2:
Input: equation = “x=x”
Output: “Infinite solutions”
Example 3:
Input: equation = “2x=x”
Output: “x=0”
2. Coding Pattern Used in Solution
The coding pattern used in the provided code is “Equation Parsing and Solving”. This pattern involves parsing a mathematical equation, extracting coefficients and constants, and solving for the variable. It is a specialized problem-solving approach for handling algebraic equations.
3. Code Implementation in Different Languages
3.1 Solve the Equation C++
class Solution {
public:
string solveEquation(string equation) {
const string lhsEquation = equation.substr(0, equation.find('='));
const string rhsEquation = equation.substr(equation.find('=') + 1);
const auto& [lhsCoefficient, lhsConstant] = calculate(lhsEquation);
const auto& [rhsCoefficient, rhsConstant] = calculate(rhsEquation);
const int coefficient = lhsCoefficient - rhsCoefficient;
const int constant = rhsConstant - lhsConstant;
if (coefficient == 0 && constant == 0)
return "Infinite solutions";
if (coefficient == 0 && constant != 0)
return "No solution";
return "x=" + to_string(constant / coefficient);
}
private:
pair<int, int> calculate(const string& s) {
int coefficient = 0;
int constant = 0;
int num = 0;
int sign = 1;
for (int i = 0; i < s.length(); ++i) {
const char c = s[i];
if (isdigit(c))
num = num * 10 + (c - '0');
else if (c == '+' || c == '-') {
constant += sign * num;
sign = c == '+' ? 1 : -1;
num = 0;
} else {
if (i > 0 && num == 0 && s[i - 1] == '0')
continue;
coefficient += num == 0 ? sign : sign * num;
num = 0;
}
}
return {coefficient, constant + sign * num};
}
};
3.2 Solve the Equation Java
class Solution {
public String solveEquation(String equation) {
int x1 = 0,x2 = 0;
int sum1=0,sum2=0;
int sign = 1;
int i=0;
boolean flag = true;
for(i=0;i<equation.length();i++){
char ch = equation.charAt(i);
if(ch == '=') flag = false;
else if(ch == 'x'){
if(flag) x1 += sign;
else x2 += sign;
sign = 1;
}
else if(Character.isDigit(ch)){
int val =0;
while(i<equation.length() && Character.isDigit(equation.charAt(i))){
val = val*10 + Character.getNumericValue(equation.charAt(i));
i++;
}
i--;
if(i<equation.length()-1 && equation.charAt(i+1) == 'x'){
i++;
if(flag) x1+=sign * val;
else x2 += sign * val;
}
else{
if(flag)sum1 += sign * val;
else sum2 += sign * val;
}
sign = 1;
}else if(ch == '-') sign = -1;
}
StringBuilder sb = new StringBuilder();
if(x1==x2 && sum1 == sum2) return "Infinite solutions";
else if(sum1 == 0 && sum2 == 0) return "x=0";
else if(x1 == x2 && ((sum1!=0)||(sum2!=0))) return "No solution";
int sum=0;
int x=0;
if(x1>x2){
x = x1 - x2;
sum = sum2-sum1;
sum = sum/x;
}
else if(x2>x1){
x = x2 - x1;
sum = sum1-sum2;
sum = sum/x;
}
sb.append("x=");
sb.append(sum);
return sb.toString();
}
}
3.3 Solve the Equation JavaScript
var solveEquation = function(equation) {
const [left, right] = equation.split('=');
const [lsv,lsc] = solve(left);
const [rsv,rsc] = solve(right);
const [variable,constant] = [lsv-rsv,rsc-lsc];
return !variable ? (lsc === rsc ? "Infinite solutions":
"No solution") : `x=${constant / variable}`
};
const solve = equation => {
let x = 0;
let num = 0;
for(let i = 0; i < equation.length; i++){
if(equation[i] === "x"){
if(equation[i - 1] === "+") x += 1;
else if(equation[i - 1] === "-") x -= 1;
else x = 1;
}else if(!isNaN(equation[i])){
let str = equation[i];
let k = i + 1;
while(!isNaN(equation[k])){
str += equation[k];
k++;
}
let res = equation[k] === "x" ? x : num;
if(equation[i - 1] === "-") res -= parseInt(str)
else if(equation[i - 1] === "+") res += parseInt(str);
else res = parseInt(str)
if(equation[k] === "x") x = res;
else num = res;
i = k;
}
}
return [x,num]
}
3.4 Solve the Equation Python
class Solution(object):
def solveEquation(self, equation):
x = a = 0
side = 1
for eq, sign, num, isx in re.findall('(=)|([-+]?)(\d*)(x?)', equation):
if eq:
side = -1
elif isx:
x += side * int(sign + '1') * int(num or 1)
elif num:
a -= side * int(sign + num)
return 'x=%d' % (a / x) if x else 'No solution' if a else 'Infinite solutions'
4. Time and Space Complexity
| Time Complexity | Space Complexity | |
| C++ | O(n) | O(n) |
| Java | O(n) | O(1) |
| JavaScript | O(n) | O(n) |
| Python | O(n) | O(1) |