Submission #878104

#	Time	Username	Problem	Language	Result	Execution time	Memory
878104		serkanrashid	Toll (BOI17_toll)	C++14	100 / 100	311 ms	54492 KiB

toll

#include <bits/stdc++.h>
#define endl "\n"

using namespace std;

struct edge
{
    int ver,dist;
    edge(){};
    edge(int vi, int di)
    {
        ver = vi;
        dist = di;
    }
    bool operator<(const edge&ed) const
    {
        return dist>ed.dist;
    }
};

const int maxn = 50005;

int k,n,m,o;
vector<edge>g[maxn],v[maxn];
unsigned int pref[maxn][5][22],suff[maxn][5][22];
unsigned int inf = -1;

void dijkstra_pref(int beg, int i, int lvl, int l, int r)
{
    pref[beg][i][lvl] = 0;
    priority_queue<edge>q;
    q.push({beg,0});
    while(!q.empty())
    {
        edge e = q.top();
        q.pop();
        if(e.dist<=pref[e.ver][i][lvl])
        {
            for(edge nb:v[e.ver])
            {
                if(l<=nb.ver/k&&nb.ver/k<=r&&nb.dist+e.dist<pref[nb.ver][i][lvl])
                {
                    nb.dist += e.dist;
                    pref[nb.ver][i][lvl] = nb.dist;
                    q.push(nb);
                }
            }
        }
    }
}

void dijkstra_suff(int beg, int i, int lvl, int l, int r)
{
    suff[beg][i][lvl] = 0;
    priority_queue<edge>q;
    q.push({beg,0});
    while(!q.empty())
    {
        edge e = q.top();
        q.pop();
        if(e.dist<=suff[e.ver][i][lvl])
        {
            for(edge nb:g[e.ver])
            {
                if(l<=nb.ver/k&&nb.ver/k<=r&&nb.dist+e.dist<suff[nb.ver][i][lvl])
                {
                    nb.dist += e.dist;
                    suff[nb.ver][i][lvl] = nb.dist;
                    q.push(nb);
                }
            }
        }
    }
}

void divide(int l, int r, int lvl)
{
    if(l>=r) return;
    int mid = (l+r)/2;
    for(int i=0;i<k;i++)
    {
        int beg = mid*k + i;
        dijkstra_pref(beg,i,lvl,l,r);
        dijkstra_suff(beg,i,lvl,l,r);
    }
    divide(l,mid-1,lvl+1);
    divide(mid+1,r,lvl+1);
}

int query(int l, int r, int lvl, int a, int b)
{
    int mid = (l+r)/2;
    if(a/k<=mid&&mid<=b/k)
    {
        long long ans = inf;
        for(int i=0;i<k;i++)
        {
            if(pref[a][i][lvl]!=inf&&suff[b][i][lvl]!=inf)
                ans = min(ans,(long long)pref[a][i][lvl]+suff[b][i][lvl]);
        }
        if(ans==inf) return -1;
        return ans;
    }
    if(b/k<mid) return query(l,mid-1,lvl+1,a,b);
    return query(mid+1,r,lvl+1,a,b);
}

void read()
{
    cin >> k >> n >> m >> o;
    int a,b,t;
    for(int i=1;i<=m;i++)
    {
        cin >> a >> b >> t;
        g[a].push_back({b,t});
        v[b].push_back({a,t});
    }
    memset(pref,-1,sizeof(pref));
    memset(suff,-1,sizeof(suff));
    divide(0,n/k,0);
    for(int i=1;i<=o;i++)
    {
        cin >> a >> b;
        cout << query(0,n/k,0,a,b) << endl;
    }
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	read();
return 0;
}

Compilation message (stderr)

toll.cpp: In function 'void dijkstra_pref(int, int, int, int, int)':
toll.cpp:37:18: warning: comparison of integer expressions of different signedness: 'int' and 'unsigned int' [-Wsign-compare]
   37 |         if(e.dist<=pref[e.ver][i][lvl])
      |            ~~~~~~^~~~~~~~~~~~~~~~~~~~~
toll.cpp:41:60: warning: comparison of integer expressions of different signedness: 'int' and 'unsigned int' [-Wsign-compare]
   41 |                 if(l<=nb.ver/k&&nb.ver/k<=r&&nb.dist+e.dist<pref[nb.ver][i][lvl])
      |                                              ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
toll.cpp: In function 'void dijkstra_suff(int, int, int, int, int)':
toll.cpp:61:18: warning: comparison of integer expressions of different signedness: 'int' and 'unsigned int' [-Wsign-compare]
   61 |         if(e.dist<=suff[e.ver][i][lvl])
      |            ~~~~~~^~~~~~~~~~~~~~~~~~~~~
toll.cpp:65:60: warning: comparison of integer expressions of different signedness: 'int' and 'unsigned int' [-Wsign-compare]
   65 |                 if(l<=nb.ver/k&&nb.ver/k<=r&&nb.dist+e.dist<suff[nb.ver][i][lvl])
      |                                              ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 10 / 10
• Subtask 3: 8 / 8
• Subtask 4: 31 / 31
• Subtask 5: 44 / 44