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leetcode.224.基本计算器(递归)

计算器

题目

- leetcode 224. 基本计算器

递归

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class Solution {
public:

//词素
struct morpheme
{
long digital;
char ops;
int type;
int priority = -1;

morpheme(int t, int d, char o, int p)
{
type = t;
digital = d;
ops = o;
priority = p;
}

morpheme()
{
}
};

string skipspace(string s)
{
string ans;

for (int i = 0; i < s.size(); i++) {
char c = s[i];
if (c != ' ') {
ans.push_back(c);
}
}
return ans;
}
void scanning(const string str, vector<morpheme>& v)
{
char morphemetype[] = { ')','+','-','*','/','(' };
int morphemetypelength = 6;

long digit = 0;
int len = str.length();
for (int i = 0; i < len; i++)
{
char c = str[i];
if (c == ' ')
{
continue;
}
bool flag = false;
for (int j = 0; j < morphemetypelength; j++)
{
if (c == morphemetype[j])
{
v.push_back(morpheme(j, 0, c, j));
flag = true;
}
}

if (flag == false)
{
digit = digit * 10 + (int)c - 0x30;

if (i == len - 1 || (str[i + 1] < '0' || str[i + 1] > '9'))
{
v.push_back(morpheme(-1, digit, '\0', -1));
digit = 0;
}
}
}
}
int recursive(vector<morpheme>& out,vector<morpheme>& in,int left,int right)
{
for (int i = left; i < right; )
{
if (in[i].type == 5)
{
vector<morpheme> outtemp2;
int bracketright = recursive(outtemp2,in, i + 1,right);
for (int j = 0; j < outtemp2.size(); j++)
{
out.push_back(outtemp2[j]);
}
i= bracketright + 1;
}
else if (in[i].type == 0)
{
long value = calculator(out, 0, out.size());
out.clear();
out.push_back(morpheme(-1, value, '\0', -1));
return i;
}
else
{
out.push_back(in[i]);
i++;
}
}
return right;
}

long calculator(vector<morpheme>& v,int left,int right)
{
vector<morpheme> r1;
long curvalue = 0;
for (int i = left; i < right;)
{
if (v[i].type == -1)
{
curvalue = v[i].digital;
i++;
}
else if (v[i].priority == 3)
{
curvalue = curvalue * v[i + 1].digital;
i += 2;
}
else if (v[i].priority == 4)
{
curvalue = curvalue / v[i + 1].digital;
i += 2;
}
else
{
r1.push_back(morpheme(-1, curvalue, '\0', -1));
r1.push_back(v[i]);
i++;
}
}
r1.push_back(morpheme(-1, curvalue, '\0', -1));

long result = 0;
curvalue = 0;
for (int i = 0; i < r1.size();)
{
if (r1[i].type == -1)
{
curvalue = r1[i].digital;
i++;
}
else if (r1[i].priority == 1)
{
curvalue = curvalue + r1[i + 1].digital;
i += 2;
}
else if (r1[i].priority == 2)
{
curvalue = curvalue - r1[i + 1].digital;
i += 2;
}
else
{
break;
}
}

result = curvalue;
return result;
}
int calculate(string s) {
string str = s;
str = skipspace(str);
vector<morpheme> in;
scanning(str, in);
vector<morpheme> out;
recursive(out,in, 0, in.size());
long result = calculator(out, 0, out.size());
return result;
}
};