Submission #152930

#	Time	Username	Problem	Language	Result	Execution time	Memory
152930		mhy908	Duathlon (APIO18_duathlon)	C++14	0 / 100	292 ms	38328 KiB

count_triplets

#include <bits/stdc++.h>
#define pb push_back
#define F first
#define S second
#define all(x) x.begin(), x.end()
using namespace std;
typedef long long LL;
int n, m;
pair<int, int> ed[200010];
vector<int> input[100010], link[100010], linkrev[100010], bcc[100010];
bool ch[100010];
int arr[100010], re, c, col[100010];
LL subtree[100010], dp[100010], dp2[100010], dp3[100010];
LL ans;
unordered_set<LL> us;
void give_dir(int num)
{
    if(ch[num])return;
    ch[num]=true;
    for(int i=0; i<input[num].size(); i++){
        if(!us.count((LL)num*200000+(LL)input[num][i])&&!us.count((LL)input[num][i]*200000+(LL)num)){
            link[num].pb(input[num][i]);
            linkrev[input[num][i]].pb(num);
            us.insert((LL)num*200000+(LL)input[num][i]);
            us.insert((LL)input[num][i]*200000+(LL)num);
            //printf("%d -> %d\n", num, input[num][i]);
        }
        give_dir(input[num][i]);
    }
}
void dfs1(int num)
{
    if(ch[num])return;
    ch[num]=true;
    for(int i=0; i<link[num].size(); i++){
        dfs1(link[num][i]);
    }
    arr[++re]=num;
}
void dfs2(int num, int color)
{
    if(col[num])return;
    col[num]=color;
    for(int i=0; i<linkrev[num].size(); i++){
        dfs2(linkrev[num][i], color);
    }
}
void tree_dp(int num)
{
    if(ch[num])return;
    ch[num]=true;
    dp[num]=subtree[num];
    dp3[num]=(subtree[num]-1)*(subtree[num]-1);
    if(bcc[num].size()==1&&ch[bcc[num][0]]){
        ans+=subtree[num]*(subtree[num]-1)*(subtree[num]-2)/2;
        return;
    }
    for(int i=0; i<bcc[num].size(); i++){
        if(ch[bcc[num][i]])continue;
        tree_dp(bcc[num][i]);
        dp[num]+=dp[bcc[num][i]];
        dp2[num]+=dp2[bcc[num][i]];
        dp2[num]+=subtree[num]*dp[bcc[num][i]];
        dp3[num]+=dp3[bcc[num][i]];
        ans+=subtree[num]*(dp2[bcc[num][i]]+dp3[bcc[num][i]]);
        ans+=subtree[num]*(subtree[num]-1)*(subtree[num]-2)/2;
        ans+=dp[bcc[num][i]]*(subtree[num]-1)*(subtree[num]-1);
    }
}
int main()
{
    scanf("%d %d", &n, &m);
    for(int i=1; i<=m; i++){
        int a, b;
        scanf("%d %d", &a, &b);
        input[a].pb(b);
        input[b].pb(a);
        ed[i].F=a;
        ed[i].S=b;
    }
    give_dir(1);
    memset(ch, 0, sizeof(ch));
    for(int i=1; i<=n; i++){
        if(!ch[i])dfs1(i);
    }
    for(int i=n; i>=1; i--){
        if(!col[arr[i]])dfs2(arr[i], ++c);
        subtree[col[arr[i]]]++;
    }
    for(int i=1; i<=m; i++){
        if(col[ed[i].F]!=col[ed[i].S]){
            bcc[col[ed[i].F]].pb(col[ed[i].S]);
            bcc[col[ed[i].S]].pb(col[ed[i].F]);
        }
    }
    for(int i=1; i<=c; i++){
        sort(all(bcc[i]));
        bcc[i].erase(unique(all(bcc[i])), bcc[i].end());
    }
    memset(ch, 0, sizeof(ch));
    for(int i=1; i<=c; i++){
        tree_dp(1);
    }
    ans*=2;
    printf("%lld", ans);
}

Compilation message (stderr)

count_triplets.cpp: In function 'void give_dir(int)':
count_triplets.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<input[num].size(); i++){
                  ~^~~~~~~~~~~~~~~~~~
count_triplets.cpp: In function 'void dfs1(int)':
count_triplets.cpp:35:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<link[num].size(); i++){
                  ~^~~~~~~~~~~~~~~~~
count_triplets.cpp: In function 'void dfs2(int, int)':
count_triplets.cpp:44:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<linkrev[num].size(); i++){
                  ~^~~~~~~~~~~~~~~~~~~~
count_triplets.cpp: In function 'void tree_dp(int)':
count_triplets.cpp:58:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<bcc[num].size(); i++){
                  ~^~~~~~~~~~~~~~~~
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:72:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~~
count_triplets.cpp:75:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~

• 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