P1341 无序字母对

https://www.luogu.com.cn/record/77844194

Luogu/P1341/P1341.cpp

@@ -0,0 +1,78 @@
+#include <iostream>
+#include <cstring>
+#include <set>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1005;
+
+int n, cnt, s, t, deg[N], ans[N];
+int g[N][N];
+std::set<char> nodes;
+
+void dfs(char u) {
+    for (int i = 1; i <= 128; i++) {
+        if (g[u][i]) {
+            g[u][i]--;
+            g[i][u]--;
+
+            dfs(i);
+        }
+    }
+
+    ans[++cnt] = u;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        char u, v;
+
+        cin >> u >> v;
+
+        g[u][v]++, g[v][u]++;
+        deg[u]++, deg[v]++;
+
+        nodes.insert(u);
+        nodes.insert(v);
+    }
+
+    int x = 0;
+
+    t = *nodes.rbegin();
+
+    for (const char &node : nodes) {
+        if (deg[node] & 1) {
+            x++;
+
+            if (!s) s = node;
+        }
+    }
+
+    if (!s) s = *nodes.begin();
+
+    if (x && x != 2) {
+        cout << "No Solution" << endl;
+
+        exit(0);
+    }
+
+    dfs(s);
+
+    if (cnt <= n) {
+        cout << "No Solution" << endl;
+    } else {
+        for (int i = cnt; i; i--) {
+            cout << (char)(ans[i]);
+        }
+        cout << endl;
+    }
+
+    return 0;
+}