'commit'

TangDou/AcWing/BipartiteGraph/860_dfs.cpp

@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+const int N = 100010, M = N << 1;
+
+int n, m;
+int color[N];
+
+// 邻接表
+int e[M], h[N], idx, ne[M];
+void add(int a, int b) {
+    e[idx] = b, ne[idx] = h[a], h[a] = idx++;
+}
+
+// u:点 c:颜色值
+bool dfs(int u, int c) {
+    color[u] = c;
+    for (int i = h[u]; ~i; i = ne[i]) {
+        int v = e[i];
+        if (!color[v]) {                  // 没有染色过
+            if (!dfs(v, 3 - c)) return 0; // 这个3-c用的太妙了
+        } else if (color[v] == c)
+            return 0; // 染色冲突
+    }
+    return 1;
+}
+
+int main() {
+    memset(h, -1, sizeof h);
+    cin >> n >> m;
+
+    while (m--) {
+        int a, b;
+        cin >> a >> b;
+        add(a, b), add(b, a);
+    }
+    bool flag = 1;
+    for (int i = 1; i <= n; i++)
+        if (!color[i]) { // 把当前点染色为1
+            if (!dfs(i, 1)) {
+                flag = 0;
+                break;
+            }
+        }
+    if (flag)
+        puts("Yes");
+    else
+        puts("No");
+    return 0;
+}