Submission #1109350

#	Time	Username	Problem	Language	Result	Execution time	Memory
1109350		mariaclara	The Kingdom of JOIOI (JOI17_joioi)	C++17	0 / 100	3 ms	6736 KiB

joioi

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef tuple<ll,ll,ll> trio;
typedef pair<int,int> pii;
const int MAXN = 2e5+5;
const ll INF = 1e9;
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define mk make_pair
#define pb push_back
#define fr first
#define sc second

int n, m, max_val, min_val = 1e9, op[4] = {0, 0, 1, -1};
int color[2005][2005], v[2005][2005];
bool vis[2005][2005];

void dfs(int x, int y, int flag) {
    vis[x][y] = 1;

    for(int i = 0; i < 4; i++) {
        int a = x + op[i], b = y + op[3-i];
        if(a <= 0 or n < a or b <= 0 or m < b) continue;
        if(!vis[a][b] and v[a][b] != -flag) dfs(a, b, flag);
    }
}

bool check(int dif) {
    int a, b, c, d;

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            color[i][j] = 0;
            if(max_val - dif >= v[i][j]) color[i][j] = 1, a = i, b = j;
            if(min_val + dif <= v[i][j]) color[i][j] = -1, c = i, d = j;
            if(a == c and b == d) return 0;
        }
    }

    // checa se os menores chegam um no outro
    memset(vis, 0, sizeof(vis));
    dfs(a,b,1);

    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= m; j++)
            if(color[i][j] == 1 and !vis[i][j]) return 0;

    // checa se os maiores chegam um no outro
    memset(vis, 0, sizeof(vis));
    dfs(c,d,-1);

    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= m; j++)
            if(color[i][j] == -1 and !vis[i][j]) return 0;

    int last = 0, cnt = 0;

    for(int j = 1; j <= m; j++)
        if(color[1][j]) cnt += (last != color[1][j]), last = color[1][j];
         
    for(int i = 1; i <= n; i++)
        if(color[i][m]) cnt += (last != color[i][m]), last = color[i][m]; 
        
    for(int j = m; j >= 1; j--)
        if(color[n][j]) cnt += (last != color[n][j]), last = color[n][j];
         
    for(int i = n; i >= 1; i--)
        if(color[i][1]) cnt += (last != color[i][1]), last = color[i][1];

    if(cnt > 3) return 0;
    return 1; 
}

int busca() {
    int l = 1, r = max_val - min_val;
    while(l <= r) {
        int mid = (l+r)/2;
        if(check(mid)) r = mid-1;
        else l = mid+1;
    }
    return r;
}
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            cin >> v[i][j];
            min_val = min(min_val, v[i][j]);
            max_val = max(max_val, v[i][j]);
        }
    }

    cout << busca();
}

Compilation message (stderr)

joioi.cpp: In function 'bool check(int)':
joioi.cpp:53:8: warning: 'd' may be used uninitialized in this function [-Wmaybe-uninitialized]
   53 |     dfs(c,d,-1);
      |     ~~~^~~~~~~~
joioi.cpp:53:8: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
joioi.cpp:45:8: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   45 |     dfs(a,b,1);
      |     ~~~^~~~~~~
joioi.cpp:45:8: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]

• Subtask 1: 0 / 15
• Subtask 2: 0 / 45
• Subtask 3: 0 / 40