1 2 4 3
3 2 1 4

(0, 0, 1, 0)

// Problem: Contest
// Contest: NowCoder
// URL: https://ac.nowcoder.com/acm/contest/21763/1021
// Memory Limit: 262144 MB
// Time Limit: 2000 ms
// 2022-04-16 15:31:39
//
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
using namespace std;

#define rep(i,l,r) for(int i=(l);i<=(r);i++)
#define per(i,l,r) for(int i=(l);i>=(r);i--)
#define ll long long
#define mset(s,t) memset(s,t,sizeof(t))
#define mcpy(s,t) memcpy(s,t,sizeof(t))
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define mp make_pair

typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> Vll;
typedef vector<pair<int, int> > vpii;
typedef vector<pair<ll, ll> > vpll;

const ll mod = 1e9 + 7;
//const ll mod = 998244353;
const double pi = acos(-1.0);
inline ll ksc(ll x,ll y,ll mod)
{
ll ans = 0;
while (y) {
if (y & 1)
ans = (ans + x) %mod;
y >>= 1;
x = (x + x) %mod;
}
return ans;
}
inline ll qmi (ll a, ll b) {
ll ans = 1;
while (b) {
if (b & 1) ans = ans * a;
a = a * a;
b >>= 1;
}
return ans;
}
inline int read () {
int x = 0, f = 0;
char ch = getchar();
while (!isdigit(ch)) f |= (ch=='-'),ch= getchar();
while (isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
return f?-x:x;
}
template<typename T> void print(T x) {
if (x < 0) putchar('-'), x = -x;
if (x >= 10) print(x/10);
putchar(x % 10 + '0');
}
inline ll sub (ll a, ll b) {
return ((a - b ) %mod + mod) %mod;
}
inline ll add (ll a, ll b) {
return (a + b) %mod;
}
// inline ll inv (ll a) {
// return qmi(a, mod - 2);
// }
const int N = 200005;
int a[N], b[N], c[N];
int n;
int p[N];
int sum[N];
void add (int x, int i) {
for (;x <= n; x += x & -x)
sum[x] += i;
}
ll query (int x) {
ll tar = 0;
for (;x; x -= x & -x)
tar += sum[x];
return tar;
}
ll get (int a[], int b[]) {
memset(sum, 0, sizeof sum);
int tmp[N];
for (int i = 1; i<= n; i ++)
tmp[a[i]] = b[i];
ll ans = 0;
for (int i = 1; i <= n; i ++) {
ans += query(n) - query(tmp[i]);
//表示求第n - tmp[i] +1的贡献,
//下标表示第几名
add (tmp[i], 1);
}
return ans;
}
void solve() {
cin >> n;
for (int i = 1; i<= n; i ++) cin >> a[i] >> b[i] >> c[i];
cout << (get(a, b) + get(a, c) + get(b, c)) / 2;
}
int main () {
// ios::sync_with_stdio(0),cin.tie(0), cout.tie(0);
int t;
t =1;
//cin >> t;
while (t --) solve();
return 0;
}

我们可以把情况表示对于一门和其他两门,有两种情况,一种是他比另外两门都低,或者都高, 贡献分别是0 / 2,2 / 2 = 1这就是对答案有1的贡献,我们最后算/2就行了, 对于树状数组求逆序对,我们可以