MLE and WA

2023205/main.cpp

@@ -1,20 +1,53 @@
 #include <stdio.h>
-int nodes[65540] = {0};
+// 并查集。并查集只关注双向连通性。
+
+struct Edge {
+    unsigned short end;
+    int next;
+};
+
+Edge edges[1050000];
+char nodes_visited[65540];
+int head[65540], len;
+
+int add_edge(int start, int terminal) {
+    edges[++len].end = terminal;
+    edges[len].next = head[start];
+    head[start] = len;
+    return 0;
+}
+
+int dfs(int start) {
+    if (nodes_visited[start] >= 1) {
+        nodes_visited[start] = 2;
+        return 0;
+    }
+    nodes_visited[start] = 1;
+    for (int j = head[start]; j != 0; j = edges[j].next) {
+        dfs(edges[j].end);
+    }
+    return 0;
+}
 
 int main() {
     int N, M;
     scanf("%d %d", &N, &M);
-    for (int i = 0; i < N; i++) {
-        int total_edge, dest_node;
-        scanf("%d", &total_edge);
-        for (int j = 0; j < total_edge; j++) {
-            scanf("%d", &dest_node);
-            nodes[dest_node]++;
+    for (int start = 0; start < N; start++) {
+        int edge_count;
+        scanf("%d", &edge_count);
+        for (int j = 0; j < edge_count; j++) {
+            int terminal;
+            scanf("%d", &terminal);
+            add_edge(start, terminal);
         }
     }
-    for (int i = 1; i < N; i++) {
-        if (nodes[i] == 0) {
-            for (int i = 0; i <= M; i++) {
+    
+    dfs(0);
+
+    for (int i  = 0; i < N; i++) {
+        if (nodes_visited[i] < 1) {
+            // Not connected!
+            for (int j = 0; j <= M; j++) {
                 printf("0\n");
             }
             return 0;
@@ -22,15 +55,17 @@ int main() {
     }
 
     printf("1\n");
+
     for (int i = 0; i < M; i++) {
         int start, end;
         scanf("%d %d", &start, &end);
-        if (end == 0 || nodes[end] > 1) {
+        if (nodes_visited[end] == 2) {
             printf("1\n");
         }
         else {
             printf("0\n");
         }
     }
+
     return 0;
 }