Added C++ solution for 0770.Basic Calculator IV

Author: ZAID646

solution/0700-0799/0770.Basic Calculator IV/solutions.cpp

@@ -0,0 +1,42 @@
+#include <bits/stdc++.h>
+using namespace std;
+struct Poly{
+    map<vector<string>, long> d;
+    Poly(long v=0){ if(v) d[{}]=v; }
+    Poly(const string &s){ d[{s}]=1; }
+};
+Poly add(const Poly &a,const Poly &b){ Poly r=a; for(auto &p:b.d) r.d[p.first]+=p.second; for(auto it=r.d.begin();it!=r.d.end();){ if(it->second==0) r.d.erase(it++); else ++it;} return r; }
+Poly sub(const Poly &a,const Poly &b){ Poly r=a; for(auto &p:b.d) r.d[p.first]-=p.second; for(auto it=r.d.begin();it!=r.d.end();){ if(it->second==0) r.d.erase(it++); else ++it;} return r; }
+Poly mul(const Poly &a,const Poly &b){ Poly r; for(auto &p:a.d) for(auto &q:b.d){ auto v=p.first; v.insert(v.end(),q.first.begin(),q.first.end()); sort(v.begin(),v.end()); r.d[v]+=p.second*q.second; } for(auto it=r.d.begin();it!=r.d.end();){ if(it->second==0) r.d.erase(it++); else ++it;} return r; }
+class Solution {
+public:
+    vector<string> basicCalculatorIV(string expr, vector<string>& evv, vector<int>& evi){
+        unordered_map<string,long> mp;
+        for(int i=0;i<evv.size();i++) mp[evv[i]] = evi[i];
+        vector<string> toks;
+        string t;
+        for(char c:expr){
+            if(c==' '){ if(!t.empty()){ toks.push_back(t); t.clear(); }}
+            else if(strchr("()+-*",c)){
+                if(!t.empty()){ toks.push_back(t); t.clear(); }
+                toks.push_back(string(1,c));
+            } else t.push_back(c);
+        }
+        if(!t.empty()) toks.push_back(t);
+        int i=0;
+        function<Poly()> parseE, parseT, parseP;
+        parseP = [&]{ string s=toks[i++]; if(s=="("){ Poly r = parseE(); i++; return r;} if(isdigit(s[0])) return Poly(stol(s)); return mp.count(s)? Poly(mp[s]) : Poly(s); };
+        parseT = [&]{ Poly r=parseP(); while(i<toks.size() && toks[i]=="*"){ i++; r = mul(r, parseP()); } return r; };
+        parseE = [&]{ Poly r=parseT(); while(i<toks.size()&&(toks[i]=="+"||toks[i]=="-")){ string op=toks[i++]; Poly p=parseT(); r = (op=="+"? add(r,p) : sub(r,p)); } return r; };
+        Poly res = parseE();
+        vector<pair<vector<string>,long>> v(res.d.begin(), res.d.end());
+        sort(v.begin(), v.end(), [](auto &a, auto &b){ if(a.first.size()!=b.first.size()) return a.first.size()>b.first.size(); return a.first<b.first; });
+        vector<string> ans;
+        for(auto &p:v) if(p.second){
+            string s = to_string(p.second);
+            for(auto &var:p.first) s += "*" + var;
+            ans.push_back(s);
+        }
+        return ans;
+    }
+};