Submission #1690634

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Source Code Expand

#include<bits/stdc++.h>
#define N 200000
using namespace std;
struct line {
    int A, B, C, n;
    double p;
} L[N];
int t[N], n;

bool cmpX(line a, line b) {
    return a.A * b.B > b.A * a.B;
}
bool cmp(line a, line b) {
    return a.p < b.p;
}
int lb(int x) {
    return x & (-x);
}
double calc(double x, int i) {
    return ((double)L[i].C - (double)L[i].A * x) / L[i].B;
}
void add(int x) {
    for(; x <= n; x += lb(x)) t[x]++;
}
int ask(int x) {
    int ret = 0;
    for(; x > 0; x -= lb(x)) ret += t[x];
    return ret;
}

int ch(double mid) {
    for(int i = 1; i <= n; i++) L[i].p = calc(mid, i);
    sort(L + 1, L + n + 1, cmp);
    for(int i = 1; i <= n; i++) t[i] = 0;
    int ret = 0;
    for(int i = 1; i <= n; i++) {
        ret += ask(L[i].n);
        add(L[i].n);
    }
    return ret;
}

double sol() {
    double l = -1e9, r = 1e9;
    for(int i = 1; i <= 80; i++) {
        double mid = (l + r) / 2;
        int tmp = ch(mid);
        if (tmp + tmp < n * (n - 1) / 2) l = mid;
        else r = mid;
    }
    return l;
}

int main() {
    cin >> n;
    for(int i = 1; i <= n; i++) scanf("%d%d%d", &L[i].A, &L[i].B, &L[i].C);
    for(int i = 1; i <= n; i++)
        if (L[i].B < 0) L[i].A *= -1, L[i].B *= - 1, L[i].C *= -1;
    sort(L + 1, L + n + 1, cmpX);
    for(int i = 1; i <= n; i++) L[i].n = i;
    double X = sol();
    for(int i = 1; i <= n; i++) swap(L[i].A, L[i].B);
    for(int i = 1; i <= n; i++)
        if (L[i].B < 0) L[i].A *= -1, L[i].B *= - 1, L[i].C *= -1;
    sort(L + 1, L + n + 1, cmpX);
    for(int i = 1; i <= n; i++) L[i].n = i;
    double Y = sol();
    printf("%.8f %.8f\n", X, Y);
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:56:75: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     for(int i = 1; i <= n; i++) scanf("%d%d%d", &L[i].A, &L[i].B, &L[i].C);
                                                                           ^

Judge Result