Submission #1118961

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118961		gdragon	Star triangles (IZhO11_triangle)	C++17	100 / 100	188 ms	13452 KiB

triangle

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 3e5 + 5;
const int inf = 1e9 + 7;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
int n;
ii a[N];
int suf[N], pre[N];
void read() {
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> a[i].fi >> a[i].se;
}
void compress() {
    vector<int> valX, valY;
    for(int i = 1; i <= n; i++) {
        valX.push_back(a[i].fi);
        valY.push_back(a[i].se);
    }
    sort(ALL(valX)); valX.erase(unique(ALL(valX)), valX.end()); 
    sort(ALL(valY)); valY.erase(unique(ALL(valY)), valY.end()); 
    for(int i = 1; i <= n; i++) {
        a[i].fi = lower_bound(ALL(valX), a[i].fi) - valX.begin() + 1;
        a[i].se = lower_bound(ALL(valY), a[i].se) - valY.begin() + 1;
    }
}
void solve() {  
    compress();
    sort(a + 1, a + n + 1);
    // for(int i = 1; i <= n; i++) cout << a[i].fi << ' ' << a[i].se << endl;
    for(int i = 1; i <= n; i++) ++suf[a[i].se];
    long long ans = 0;
    for(int i = 1; i <= n; i++) {
        int j = i;
        while(j <= n && a[j].fi == a[i].fi) {
            --suf[a[j].se];
            ++j;
        } 
        --j;
        long long lef = 0, rig = 0;
        for(int k = i; k <= j; k++) {
            ans += 1LL * pre[a[k].se] * (k - i);
            ans += lef;
            ans += 1LL * suf[a[k].se] * (k - i);
            ans += rig;
            lef += pre[a[k].se];
            rig += suf[a[k].se];
            ++pre[a[k].se];
        }
        i = j;
    }
    cout << ans;
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

// rmq - rmq2d
// hash
// fw - fw2d
// segtree

Compilation message (stderr)

triangle.cpp: In function 'int main()':
triangle.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
triangle.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100