#include <bits/stdc++.h> using namespace std; #define fi first #define se second #define ll long long #ifdef LOCAL #include "algo/debug.h" #else #define debug(...) 42 #endif template <class T> bool ckmax(T &a, T b) { return a < b ? (a = b, true) : false; } template <class T> bool ckmin(T &a, T b) { return a > b ? (a = b, true) : false; } const int MAXN = 2005; int a[MAXN][MAXN], b[MAXN][MAXN], lim = 0, h, w; void flip() { for (int i = 1; i <= h; i++) { for (int j = 1; j <= w; j++) { b[j][h - i + 1] = a[i][j]; } } swap(h, w); for (int i = 1; i <= h; i++) { for (int j = 1; j <= w; j++) { a[i][j] = b[i][j]; } } } bool ok(int val) { int curMax = 0, mx = 0, mn = 1e9, pos = w; for (int i = 1; i <= h; i++) { for (int j = 1; j <= pos; j++) { if (lim - a[i][j] > val) { pos = j - 1; break; } ckmax(curMax, a[i][j]); } for (int j = pos + 1; j <= w; j++) { ckmax(mx, a[i][j]); ckmin(mn, a[i][j]); } } return (curMax == lim && mx - mn <= val); } bool check(int val) { for (int i = 0; i < 4; i++) { if (ok(val)) return 1; flip(); } return 0; } int main() { #define NAME "test" if (fopen(NAME".inp", "r")) { freopen(NAME".inp", "r", stdin); freopen(NAME".out", "w", stdout); } ios_base::sync_with_stdio(false); cin.tie(nullptr); cin >> h >> w; for (int i = 1; i <= h; i++) { for (int j = 1; j <= w; j++) { cin >> a[i][j]; ckmax(lim, a[i][j]); } } int l = 0, r = 1e9, ans; while (l <= r) { int mid = (l + r) >> 1; if (check(mid)) r = (ans = mid) - 1; else l = mid + 1; } cout << ans << '\n'; return 0; }

joioi.cpp: In function 'int main()':
joioi.cpp:65:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |         freopen(NAME".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
joioi.cpp:66:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |         freopen(NAME".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~