Submission #393967

#	Time	Username	Problem	Language	Result	Execution time	Memory
393967		79brue	Duathlon (APIO18_duathlon)	C++14	0 / 100	75 ms	21152 KiB

count_triplets

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int n, m;
vector<int> link[100002];
ll ans;

void input();
void makeBCC();

int main(){
    input();
    makeBCC();
    printf("%lld", ans);
}

void input(){
    scanf("%d %d", &n, &m);
    for(int i=1; i<=m; i++){
        int x, y;
        scanf("%d %d", &x, &y);
        link[x].push_back(y);
        link[y].push_back(x);
    }
}

bool seen[100002];
ll seenCnt;

int dfsn[100002];
int dcnt;
stack<pair<int, int> > stk;
vector<vector<pair<int, int> > > BCC;

int dfs(int x, int prv = -1){
    int result = dfsn[x] = ++dcnt;
    seenCnt++;
    for(auto y: link[x]){
        if(prv == y) continue;
        if(dfsn[x] > dfsn[y]) stk.push(make_pair(x, y));
        if(dfsn[y] > 0) result = min(result, dfsn[y]);
        else{
            int tmp = dfs(y, x);
            result = min(result, tmp);
            if(tmp >= dfsn[x]){
                vector<pair<int, int> > currBCC;
                while(!stk.empty() && stk.top() != make_pair(x, y)){
                    currBCC.push_back(stk.top());
                    stk.pop();
                }
                currBCC.push_back(stk.top());
                stk.pop();
                BCC.push_back(currBCC);
            }
        }
    }
    return result;
}

void makeBCC(){
    for(int i=1; i<=n; i++){
        if(!seen[i]){
            seenCnt = 0;
            dfs(i);
            ans += seenCnt * (seenCnt-1) * (seenCnt-2) / 3;
        }
    }
}

Compilation message (stderr)

count_triplets.cpp: In function 'void input()':
count_triplets.cpp:21:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   21 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
count_triplets.cpp:24:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   24 |         scanf("%d %d", &x, &y);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10