Submission #989981

#	Time	Username	Problem	Language	Result	Execution time	Memory
989981		maithehung123	Mobile (BOI12_mobile)	C++14	100 / 100	902 ms	35436 KiB

mobile

#include<bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define BIT(i) (1LL << (i))
#define GBIT(mask,i) (((mask) >> (i)) & 1)
#define ALL(v) v.begin(),v.end()
#define pb push_back
#define sz(v) ((int)v.size())
#define FOR(i,a,b) for(int i = a; i <= b; ++i)
#define FOD(i,a,b) for(int i = a; i >= b; --i)

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int inf = 2e9 + 7;
const long long infll = 1e18 + 7;

template<class T1,class T2> bool maximize(T1 &a,T2 b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}

template<class T1,class T2> bool minimize(T1 &a,T2 b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}

#define MAX 1000005
int n;
int L;
pll a[MAX];

bool check(long double x) {
    long double cur = 0.0;
    FOR(i,1,n) {
        long double delta = sqrt(x * x - 1.0 * a[i].se * a[i].se);
        long double left = a[i].fi - delta,right = a[i].fi + delta;
        if(left <= cur) maximize(cur,right);
    }
    return cur >= L;
}

void process() {
    cin >> n >> L;
    FOR(i,1,n) cin >> a[i].fi >> a[i].se;
    long double l = 0,r = 1e9 + 7,mid,res;
    while(r - l >= 1e-5) {
        mid = (l + r) / 2;
        if(check(mid)) r = mid,res = mid;
        else l = mid;
    }
    cout << fixed << setprecision(6) << res;
}

int main () {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    #define TASK ""
    if(fopen(TASK".inp","r")) {
        freopen(TASK".inp","r",stdin);
        freopen(TASK".out","w",stdout);
    }

    if(fopen("main.inp","r")) {
        freopen("main.inp","r",stdin);
        freopen("main.out","w",stdout);
    }

    srand(time(0));

    process();

    cerr << "\n" << (double)clock() / CLOCKS_PER_SEC * 1000 << "ms";
    return 0;
}

Compilation message (stderr)

mobile.cpp: In function 'int main()':
mobile.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);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
mobile.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);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
mobile.cpp:76:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |         freopen("main.inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
mobile.cpp:77:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   77 |         freopen("main.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 5 / 5
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• Subtask 21: 5 / 5