Tree Isomorphisms solution correction

Author: mrsac7

src/1700 - Tree Isomorphism I.cpp

@@ -5,22 +5,21 @@ Author: Sachin Srivastava (mrsac7)
 */
 #include<bits/stdc++.h>
 using namespace std;
-
+ 
 #define int long long
 #define endl '\n'
-
-string dfs(int s, int p, vector<int> adj[]) {
-    vector<string> v;
+ 
+map<vector<int>,int> mp;
+int idx = 0;
+int dfs(int s, int p, vector<int> adj[]) {
+    vector<int> v;
     for (auto i: adj[s]) {
         if (i != p) 
             v.push_back(dfs(i, s, adj));
     }
     sort(v.begin(), v.end());
-    string ans = "(";
-    for (auto i: v)
-        ans += i;
-    ans += ')';
-    return ans;
+    if (!mp.count(v)) mp[v] = idx++;
+    return mp[v];
 }
 signed main(){
     ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
@@ -43,8 +42,8 @@ signed main(){
             adj2[x].push_back(y);
             adj2[y].push_back(x);
         }
-        string s1 = dfs(1, -1, adj1);
-        string s2 = dfs(1, -1, adj2);
+        int s1 = dfs(1, -1, adj1);
+        int s2 = dfs(1, -1, adj2);
         if (s1 == s2)
             cout<<"YES";
         else cout<<"NO";

src/1701 - Tree Isomorphism II.cpp

@@ -5,10 +5,10 @@ Author: Sachin Srivastava (mrsac7)
 */
 #include<bits/stdc++.h>
 using namespace std;
-
+ 
 #define int long long
 #define endl '\n'
-
+ 
 vector<int> center(int n, vector<int> adj[]) {
     int deg[n+1] = {0};
     vector<int> v;
@@ -32,18 +32,18 @@ vector<int> center(int n, vector<int> adj[]) {
     }
     return v;
 }
-string dfs(int s, int p, vector<int> adj[]) {
-    vector<string> v;
+map<vector<int>, int> mp;
+int idx = 0;
+
+int dfs(int s, int p, vector<int> adj[]) {
+    vector<int> v;
     for (auto i: adj[s]) {
         if (i != p) 
             v.push_back(dfs(i, s, adj));
     }
     sort(v.begin(), v.end());
-    string ans = "(";
-    for (auto i: v)
-        ans += i;
-    ans += ')';
-    return ans;
+    if (!mp.count(v)) mp[v] = idx++;
+    return mp[v];
 }
 signed main(){
     ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
@@ -67,10 +67,10 @@ signed main(){
             adj2[y].push_back(x);
         }
         vector<int> v1 = center(n, adj1), v2 = center(n, adj2);
-        string s1 = dfs(v1[0], -1, adj1);
+        int s1 = dfs(v1[0], -1, adj1);
         int f = 0;
         for (auto s: v2) {
-            string s2 = dfs(s, -1, adj2);
+            int s2 = dfs(s, -1, adj2);
             if (s1 == s2)
                 f = 1;
         }