P2731 [USACO3.3]骑马修栅栏 Riding the Fences

https://www.luogu.com.cn/record/77837475

Luogu/P2731/P2731.cpp

@@ -0,0 +1,61 @@
+#include <iostream>
+#include <algorithm>
+#include <limits>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 505;
+
+int m, g[N][N], d[N];
+int min = std::numeric_limits<int>::max(),
+    max = std::numeric_limits<int>::min();
+int cnt, ans[N << 2];
+
+void dfs(int u) {
+    for (int i = min; i <= max; 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 >> m;
+
+    while (m--) {
+        int u, v;
+
+        cin >> u >> v;
+
+        g[u][v]++, g[v][u]++;
+        d[u]++, d[v]++;
+
+        min = std::min({min, u, v});
+        max = std::max({max, u, v});
+    }
+
+    int s = min;
+    for (int i = min; i <= max; i++) {
+        if (d[i] & 1) {
+            s = i;
+            break;
+        }
+    }
+
+    dfs(s);
+
+    for (int i = cnt; i; i--) {
+        cout << ans[i] << endl;
+    }
+
+    return 0;
+}