제출 #288462

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
288462		shayan_p	도시들 (IOI15_towns)	C++17	61 / 100	25 ms	512 KiB

towns

#include<bits/stdc++.h>
#include "towns.h"

#define F first
#define S second
#define PB push_back
#define sz(s) (int(s.size()))
#define bit(n, k) (((n)>>(k))&1)

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef long double ld;

const int maxn = 1e5 + 10, mod = 1e9 + 7, inf = 1e9 + 7;

int n;
int ds[2][maxn], h[maxn], D[maxn];

int far(int u, int o){
    ds[o][u] = 0;
    for(int i = 0; i < n; i++){
	if(i != u)
	    ds[o][i] = getDistance(u, i);
    }
    int mx = 0;
    for(int i = 0; i < n; i++){
	if(ds[o][mx] < ds[o][i])
	    mx = i;
    }
    return mx;
}
bool same(int a, int b){
    return getDistance(a, b) < h[a] + h[b];
}

int hubDistance(int n, int sub){
    ::n = n;
    int A = far(0, 0);
    int B = far(A, 0);
    far(B, 1);
    vector<int> vec;
    int R = inf;
    map<int, int> mp;
    for(int i = 0; i < n; i++){
	h[i] = (ds[0][i] + ds[1][i] - ds[0][B]) / 2;
	D[i] = ds[0][i] - h[i];
	vec.PB(D[i]);
	R = min(R, max(D[i], ds[0][B] - D[i]));
	mp[D[i]]++;
    }
    
    if(sub == 2)
	return R;
    
    int sm = 0;
    vector<pii> Ds;    
    for(pii p : mp){
	sm+= p.S;
	if(max(p.F, ds[0][B] - p.F) == R){
	    Ds.PB({p.F, sm});
	}
    }
    assert(!Ds.empty());
    assert(sz(Ds) <= 2);
    int bstD = Ds[0].F;
    if(sz(Ds) == 2){
	int A = Ds[0].S, B = n - Ds[0].S;
	if(A < B)
	    bstD = Ds[1].F;
    }
    sm = 0;
    for(pii p : mp){
	if(p.F < bstD)
	    sm+= p.S;
    }
    if(sm + sm > n)
	return -R;
    sm = 0;
    for(pii p : mp){
	if(p.F > bstD)
	    sm+= p.S;
    }
    if(sm + sm > n)
	return -R;

    if(mp[bstD] * 2 <= n)
	return R;

    if(sub == 4)
	return -R;
    
    int U = -1, CNT = 0;
    for(int i = 0; i < n; i++){
	if(D[i] == bstD){
	    if(CNT == 0 || same(U, i))
		U = i, CNT++;
	    else
		CNT--;
	}
    }
    if(CNT == 0)
	return R;
    CNT = 1;
    for(int i = 0; i < n; i++){
	if(D[i] == bstD && i != U && same(U, i))
	    CNT++;
    }
    if(CNT + CNT <= n)
	return R;
    return -R;
}

컴파일 시 표준 에러 (stderr) 메시지

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:38:31: warning: declaration of 'n' shadows a global declaration [-Wshadow]
   38 | int hubDistance(int n, int sub){
      |                               ^
towns.cpp:18:5: note: shadowed declaration is here
   18 | int n;
      |     ^
towns.cpp:69:6: warning: declaration of 'A' shadows a previous local [-Wshadow]
   69 |  int A = Ds[0].S, B = n - Ds[0].S;
      |      ^
towns.cpp:40:9: note: shadowed declaration is here
   40 |     int A = far(0, 0);
      |         ^
towns.cpp:69:19: warning: declaration of 'B' shadows a previous local [-Wshadow]
   69 |  int A = Ds[0].S, B = n - Ds[0].S;
      |                   ^
towns.cpp:41:9: note: shadowed declaration is here
   41 |     int B = far(A, 0);
      |         ^

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 10 / 10
• Subtask 5: 13 / 13
• Subtask 6: 0 / 39