Submission #1035112

#	Time	Username	Problem	Language	Result	Execution time	Memory
1035112		vjudge1	Pipes (CEOI15_pipes)	C++14	90 / 100	799 ms	65536 KiB

pipes

    #include <iostream>
    #include <vector>
    using namespace std;
     
    const int N = 1e5+2;
    struct dsu {
    	int e[N];
    	int find(int &x) { return e[x] < 0 ? x : e[x] = find(e[x]); }
    	bool join(int a, int b) {
    		a = find(a), b = find(b);
    		if (a == b) return false;
    		if (e[a] > e[b]) swap(a, b);
    		e[a] += e[b]; e[b] = a;
    		return true;
    	}
    } d1, d2;
    vector<int> g[N];
    int timer=0;
    void dfs(int at, int par) {
    	d1.e[at]=d2.e[at]=++timer;
    	for(int &to:g[at]) {
    		if(to == par) {
    			par+=N;
    			continue;
    		}
    		if(d2.e[to]) {
    			d1.e[at]=min(d1.e[at], d2.e[to]);		
    		} else {
    			dfs(to, at);
    			d1.e[at]=min(d1.e[at], d1.e[to]);
    		}
    	}
    	if(par>N)par-=N;
    	if(d1.e[at] == d2.e[at] and at!=par) {
    		printf("%d %d\n", at, par);
    	}
    }
    int n, m, u, v;
    int main() {
    	srand(time(0));
     
    	scanf("%d %d", &n, &m);
    	//nt u, v;
    	for(int i = 1;i<N;i++)d1.e[i]=d2.e[i]=-1;
    	for(int i = 0;i<m;i++) {
    		scanf("%d %d", &u, &v);
    		if((d1.join(u, v) || d2.join(u, v))) {
    			g[u].push_back(v);
    			g[v].push_back(u);
    		}
    	}
    	for(int i = 1;i<N;i++)d1.e[i]=d2.e[i]=0;
    	for(int i= 1;i<=n;i++) {
    		if(!d1.e[i]) {
    			dfs(i, i);
    		}
    	}
    }

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:42:11: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |      scanf("%d %d", &n, &m);
      |      ~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:46:12: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |       scanf("%d %d", &u, &v);
      |       ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 0 / 10