Submission #1207834

#	Time	Username	Problem	Language	Result	Execution time	Memory
1207834		Madhav_1608	Tracks in the Snow (BOI13_tracks)	C++20	19.79 / 100	1195 ms	221272 KiB

tracks

#include <iostream>
#include <stack>
#include <queue>
#include <string>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <climits>
#include <cmath>
#include <unordered_map>
#include <unordered_set>
#include <numeric>
#include <iomanip>
#include <cstring>
#include <stdio.h>
#include <assert.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<long long> vll;
typedef pair<ll,ll> pll;
#define double long double
#define F first
#define S second
const double eps = 1e-9; 
#define FOR(i,a,b) for(long long i=a;i<b;i++)
#define all(v) v.begin(),v.end()
template <typename I>
void print(vector<I> &v){
    FOR(i,0,v.size()){cout << v[i] << " ";}
    cout << "\n";
}
ll gcd(ll a,ll b){
    if(a==0){return b;}
    else if(b==0){return a;}
    else if(a<b){return gcd(b%a,a);}
    else{return gcd(a%b,b);}
}
ll lcm(ll a,ll b){
    return (a/gcd(a,b))*b;
}
void setIO(string name = "") {
    freopen((name + ".in").c_str(), "r", stdin); // see /general/input-output
    freopen((name + ".out").c_str(), "w", stdout);
}
void init_code(){
    #ifndef ONLINE_JUDGE
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    #endif
}
void solve(){
    // store very big numbers may mean log2
    ll h,w;
    cin >> h >> w;
    vector<string> grid(h);
    FOR(i,0,h) cin >> grid[i];

    vector<vll> dist(h,vll(w,INT_MAX));
    dist[0][0] = 1;
    deque<pll> d;
    vector<vector<bool>> visited(h,vector<bool>(w,false));
    d.push_front({0,0});
    while(!d.empty()){
        pll curr = d.front();
        d.pop_front();
        if(visited[curr.F][curr.S]) continue;
        visited[curr.F][curr.S] = true;
        if(curr.F>0){
            ll alt = dist[curr.F][curr.S];
            ll wt = 0;
            if(grid[curr.F][curr.S]!=grid[curr.F-1][curr.S]) wt++;
            if((alt+wt)<dist[curr.F-1][curr.S]){
                dist[curr.F-1][curr.S] = alt+wt;
                if(wt==0){
                    d.push_front({curr.F-1,curr.S});
                }
                else{
                    d.push_back({curr.F-1,curr.S});
                }
            }
        }
        if(curr.S>0){
            ll alt = dist[curr.F][curr.S];
            ll wt = 0;
            if(grid[curr.F][curr.S]!=grid[curr.F][curr.S-1]) wt++;
            if((alt+wt)<dist[curr.F][curr.S-1]){
                dist[curr.F][curr.S-1] = alt+wt;
                if(wt==0){
                    d.push_front({curr.F,curr.S-1});
                }
                else{
                    d.push_back({curr.F,curr.S-1});
                }
            }
        }
        if(curr.F<(h-1)){
            ll alt = dist[curr.F][curr.S];
            ll wt = 0;
            if(grid[curr.F][curr.S]!=grid[curr.F+1][curr.S]) wt++;
            if((alt+wt)<dist[curr.F+1][curr.S]){
                dist[curr.F+1][curr.S] = alt+wt;
                if(wt==0){
                    d.push_front({curr.F+1,curr.S});
                }
                else{
                    d.push_back({curr.F+1,curr.S});
                }
            }
        }
        if(curr.S<(w-1)){
            ll alt = dist[curr.F][curr.S];
            ll wt = 0;
            if(grid[curr.F][curr.S]!=grid[curr.F][curr.S+1]) wt++;
            if((alt+wt)<dist[curr.F][curr.S+1]){
                dist[curr.F][curr.S+1] = alt+wt;
                if(wt==0){
                    d.push_front({curr.F,curr.S+1});
                }
                else{
                    d.push_back({curr.F,curr.S+1});
                }
            }
        }
    }
    ll ans = 0;
    FOR(i,0,h){
        FOR(j,0,w){
            if(grid[i][j]=='.') continue;
            ans = max(ans,dist[i][j]);
        }
    }
    cout << ans << "\n";
}

signed main(){
    //setIO
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    // init_code();
    ll t=1;
    // cin >> t;
    while(t--){
        solve();
    }
    return 0;
}

Compilation message (stderr)

tracks.cpp: In function 'void setIO(std::string)':
tracks.cpp:45:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |     freopen((name + ".in").c_str(), "r", stdin); // see /general/input-output
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:46:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |     freopen((name + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp: In function 'void init_code()':
tracks.cpp:50:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |     freopen("input.txt","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:51:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |     freopen("output.txt","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6.6667 / 30
• Subtask 2: 13.125 / 70