add final exam AC code

exercise/final/final.cpp

@@ -0,0 +1,62 @@
+#include <iostream>
+#include <vector>
+#include <map>
+#include <cstring>
+using namespace std;
+
+int G[103][103];
+vector<int> visited;
+map<int, int> mp;
+int n;
+
+bool flag = false;
+
+void dfs(int now, int end){
+    visited[now] = 1;
+    mp[now]++;
+    if(now == end){
+        flag = true;
+        return;
+    }
+    for(int i = 0; i < n; ++i){
+        if(G[now][i] && !visited[i]){
+            dfs(i, end);
+        }
+    }
+    visited[now] = 0;
+    if(!flag)   mp[now]--;
+}
+
+int main(){
+    int t; cin >> t;
+    while(t--){
+        memset(G, 0, sizeof(G));
+        cin >> n;
+        visited.assign(n+1, 0);
+        for(int i = 0; i < n-1; ++i){
+            int x, y; cin >> x >> y;
+            G[x][y] = 1;
+            G[y][x] = 1;
+        }
+        int q; cin >> q;
+        while(q--){
+            visited.assign(n+1, 0);
+            mp.clear();
+            int x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
+            dfs(x1, x2);
+            visited.assign(n+1, 0);
+            dfs(y1, y2);
+            bool print = false;
+            for(auto [x, y]: mp){
+                if(y == 2){
+                    print = true;
+                    cout << "A\n"
+                    break;
+                }
+            }
+            if(!print)  cout << "B\n";
+        }
+    }
+
+    return 0;
+}

exercise/final/final2.cpp

@@ -0,0 +1,68 @@
+#include <iostream>
+#include <vector>
+#include <map>
+#include <cstring>
+using namespace std;
+
+int G[103][103];
+vector<int> visited;
+int n;
+int prev[103];
+
+void dfs(int now){
+    visited[now] = 1;
+    for(int i = 0; i < n; ++i)
+        if(G[now][i] && !visited[i])
+            dfs(i), prev[i] = now;
+}
+
+int main(){
+    int t; cin >> t;
+    while(t--){
+        memset(G, 0, sizeof(G));
+        cin >> n;
+        visited.assign(n+1, 0);
+        for(int i = 0; i < n-1; ++i){
+            int x, y; cin >> x >> y;
+            G[x][y] = 1;
+            G[y][x] = 1;
+        }
+        int q; cin >> q;
+        while(q--){
+            int x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
+            vector<int> p1, p2;
+            memset(prev, 0, sizeof(prev));
+            visited.assign(n+1, 0);
+            dfs(x1);
+            int start = prev[x1] = -1;
+            int end = x2;
+            while(start != end){
+                p1.push_back(end);
+                end = prev[end];
+            }
+
+            memset(prev, 0, sizeof(prev));
+            visited.assign(n+1, 0);
+            dfs(y1);
+            start = prev[y1] = -1;
+            end = y2;
+            while(start != end){
+                p2.push_back(end);
+                end = prev[end];
+            }
+
+            for(auto x:p1){
+                for(auto y:p2){
+                    if(x==y){
+                        cout << "A\n";
+                        goto end;
+                    }
+                }
+            }
+            cout << "B\n";
+            end:;
+        }   
+    }
+
+    return 0;
+}