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leetcode640.java
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62 lines (59 loc) · 1.89 KB
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package leetcode;
import java.util.ArrayList;
import java.util.List;
public class leetcode640 {
public String solveEquation(String equation) {
String []lr=equation.split("=");
int lhs=0,rhs=0;// lhs代表左侧x的系数，rhs代表右侧整数
for (String x:
breakIt(lr[0])) {
if (x.indexOf("x")>=0){ //如果式子是nx
lhs+=Integer.parseInt(coeff(x));
}else{
rhs-=Integer.parseInt(x);
}
}
for (String x:
breakIt(lr[1])) {
if (x.indexOf("x")>=0){ //如果式子是nx
lhs-=Integer.parseInt(coeff(x));
}else{
rhs+=Integer.parseInt(x);
}
}
if (lhs==0){
if (rhs==0)
return "Infinite solutions";
else
return "No solution";
}
return "x="+rhs/lhs;
}
//
public String coeff(String x) {
if (x.length()>1&&x.charAt(x.length()-2)>='0'&&x.charAt(x.length()-2)<='9'){
//x.charAt(x.length()-2)>'0'&&x.charAt(x.length()-2)<'9' 是为了处理+x/-x的意外情况
return x.replace("x","");
}
return x.replace("x","1");
}
// 拆解字符串
public List< String > breakIt(String s) {
List<String> res=new ArrayList<>(); //拆解字符串
String r=""; //过渡字符串
for (int i = 0; i <s.length() ; i++) {
if (s.charAt(i)=='+'||s.charAt(i)=='-'){ //如果遇见符号说明是上一个子式录入完毕
if (r.length()>0)
res.add(r);
r=""+s.charAt(i); // 加上符号
}else{
r+=s.charAt(i);
}
}
res.add(r);
return res;
}
public static void main(String[] args) {
new leetcode640().solveEquation("99x=99");
}
}