640. Solve the Equation
Explanation
To solve this problem, we need to parse the equation and separate the coefficients of x and the constants on both sides of the equation. Then we simplify the equation by moving all x terms to one side and all constant terms to the other side. Finally, we calculate the value of x and handle cases where there are no solutions or infinite solutions.
Here is the step-by-step algorithm:
- Parse the equation to separate coefficients of
xand constants on both sides. - Simplify the equation by moving all
xterms to one side and all constant terms to the other side. - Calculate the value of
x. - Handle cases where there are no solutions or infinite solutions.
Time complexity: O(n) where n is the length of the equation.
Space complexity: O(1)
class Solution {
public String solveEquation(String equation) {
int xCoeff = 0, constant = 0;
int sign = 1;
int n = equation.length();
int i = 0;
while (i < n) {
int j = i + 1;
while (j < n && equation.charAt(j) != '+' && equation.charAt(j) != '-') {
j++;
}
String term = equation.substring(i, j);
if (term.contains("x")) {
if (term.equals("x") || term.equals("+x")) {
xCoeff += sign;
} else if (term.equals("-x")) {
xCoeff -= sign;
} else {
xCoeff += sign * Integer.parseInt(term.substring(0, term.length() - 1));
}
} else {
constant += sign * Integer.parseInt(term);
}
if (j < n && equation.charAt(j) == '-') {
sign = -1;
} else {
sign = 1;
}
i = j + 1;
}
if (xCoeff == 0) {
if (constant == 0) {
return "Infinite solutions";
} else {
return "No solution";
}
} else {
return "x=" + (-constant / xCoeff);
}
}
}Code Editor (Testing phase)
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