update

P4017/P4017.cpp

@@ -1,39 +1,71 @@
 #include <iostream>
 #include <ranges>
 #include <queue>
+#include <stdio.h>
 
 using std::cin,std::cout,std::iostream;
 static const constexpr auto range {std::ranges::views::iota};
 
-static const constexpr int MOD {80112002}, MAX_TYPES {(int)5e3+5}, MAX_REL_SHIPS {(int)5e5+5};
+static const constexpr int MOD {80112002}, MAX_TYPES {(int)5e3+5} /*, MAX_REL_SHIPS {(int)5e5+5}*/;
-static int types, rel_ships, a, b, in_degree[MAX_REL_SHIPS], out_degree[MAX_REL_SHIPS];
+static int types, rel_ships, a, b, in_degree[MAX_TYPES], out_degree[MAX_TYPES], link_nums[MAX_TYPES], ans;
-std::queue<int> q;
+static std::queue<int> q;
-std::vector<int> next[MAX_REL_SHIPS];
+static std::vector<int> next[MAX_TYPES];
+
+class ReadInt{
+    char c;
+    int w,n;
+public:
+    ReadInt &operator>>(int &num){
+        c=0,w=1,n=0;
+        while(!isdigit(c)){
+            if(c=='-')w=-1;
+            c = (char)getchar();
+        }
+        while(isdigit(c)){
+            n=n*10+(c-'0');
+            c = (char)getchar();
+        }
+        num = n*w;
+        return *this;
+    }
+};
+
+static ReadInt readint;
+
+#define cin readint
 
 int main(){
-    iostream::sync_with_stdio(false);
-
     cin>>types>>rel_ships;
-    for(const int _:range(1,rel_ships+1)){
+    for([[maybe_unused]] const int _:range(1,rel_ships+1)){
         cin>>a>>b;
         next[a].push_back(b);
         in_degree[b]++;
         out_degree[a]++;
     }
 
-    for(const int i:range(1, rel_ships+1)){
+    for(const int i:range(1, types+1)){
         if(in_degree[i]==0){
             q.push(i);
+            link_nums[i] = 1;
         }
     }
 
-    while(q.empty()==false){
+    while(!q.empty()){
         auto front {q.front()};
         q.pop();
         for(auto i:next[front]){
+            link_nums[i] = (link_nums[i] + link_nums[front])%MOD;
             if(--in_degree[i]==0){
                 q.push(i);
             }
         }
     }
+
+    for(auto i:range(1,types+1)){
+        if(out_degree[i]==0){
+            ans = (ans + link_nums[i]) % MOD;
+        }
+    }
+
+    cout<<ans<<"\n";
 }