Submission #281886

#	Time	Username	Problem	Language	Result	Execution time	Memory
281886		SamAnd	Rail (IOI14_rail)	C++17	56 / 100	920 ms	98828 KiB

rail

#include "rail.h"
#include <bits/stdc++.h>
using namespace std;
#define m_p make_pair
#define fi first
#define se second
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
typedef long long ll;
const int N = 5003;

int n;

int ans[N][N];
int qry(int x, int y)
{
    if (ans[x][y] != -1)
        return ans[x][y];
    return ans[x][y] = ans[y][x] = getDistance(x, y);
}

bool c[N];
int getnext(int s, int location[], int stype[])
{
    int minu = N * 5;
    int minx;
    for (int x = 0; x < n; ++x)
    {
        if (s == x)
            continue;
        if (qry(s, x) < minu)
        {
            minu = qry(s, x);
            minx = x;
        }
    }
    if (stype[s] == 1)
    {
        stype[minx] = 2;
        location[minx] = location[s] + qry(s, minx);
    }
    else
    {
        stype[minx] = 1;
        location[minx] = location[s] - qry(s, minx);
    }

    if (!c[minx])
        return minx;

    int minuu = N * 5;
    int minxx;

    for (int x = 0; x < n; ++x)
    {
        if (c[x])
            continue;
        if (qry(s, x) < qry(minx, x))
        {
            if (qry(s, x) < minuu)
            {
                minuu = qry(s, x);
                minxx = x;
            }
        }
    }

    if (minuu == N * 5)
        return -1;

    if (stype[s] == 1)
    {
        stype[minxx] = 2;
        location[minxx] = location[s] + qry(s, minxx);
    }
    else
    {
        stype[minxx] = 1;
        location[minxx] = location[s] - qry(s, minxx);
    }

    return minxx;
}

void dfs(int x, int location[], int stype[])
{
    c[x] = true;
    while (1)
    {
        int h = getnext(x, location, stype);
        if (h == -1)
            break;
        dfs(h, location, stype);
    }
}

void findLocation(int N_, int first, int location[], int stype[])
{
    n = N_;

    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            if (i == j)
                continue;
            ans[i][j] = -1;
        }
    }

    location[0] = first;
    stype[0] = 1;

    dfs(0, location, stype);
}

Compilation message (stderr)

rail.cpp: In function 'int getnext(int, int*, int*)':
rail.cpp:17:17: warning: 'minx' may be used uninitialized in this function [-Wmaybe-uninitialized]
   17 |     if (ans[x][y] != -1)
      |         ~~~~~~~~^
rail.cpp:26:9: note: 'minx' was declared here
   26 |     int minx;
      |         ^~~~

• Subtask 1: 8 / 8
• Subtask 2: 22 / 22
• Subtask 3: 26 / 26
• Subtask 4: 0 / 44