This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
using namespace std;
#define N 2005
#define F first
#define S second
#define ll long long
ll n,m,a[N][N],b[N][N],ans=2e9;
bool cal(ll n,ll m,ll v){
bitset<N> dp[N];
for(int i=0;i<=n;i++) dp[i] = 1;
for(int i=0;i<=m;i++) dp[n+1][i] = true;
for(int i=n;i>0;i--) for(int j=1;a[i][j]<=v&&dp[i+1][j]&&dp[i][j-1];j++) dp[i][j]=true;
if(!dp[n][1]) return false;
if(dp[1][m]) return true;
ll mn[2], mx[2];
mn[0] = mn[1] = 1e9;
mx[0] = mx[1] = 0;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
mn[dp[i][j]]=min(mn[dp[i][j]],a[i][j]);
mx[dp[i][j]]=max(mx[dp[i][j]],a[i][j]);
}
}
// printf(">> %d : %d %d %d %d\n",v,mx1,mn1,mx0,mn0);
ans = min(ans,max(mx[0]-mn[0],mx[1]-mn[1]));
if(mn[1] >= mn[0]) return false;
return mx[1]-mn[1] > mx[0]-mn[0];
}
void sol(ll n,ll m){
ll be = 0,ed = 1e9;
while(be <= ed){
ll mid = (be+ed)/2;
if(cal(n,m,mid)) ed = mid-1;
else be = mid+1;
}
}
int main(){
scanf("%lld%lld",&n,&m);
for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) scanf("%lld",&a[i][j]);
sol(n,m);
for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) b[i][j] = a[i][j];
for(int i=1;i<=m;i++) for(int j=1;j<=n;j++) a[i][j] = b[n-j+1][i];
sol(m,n);
for(int i=1;i<=m;i++) for(int j=1;j<=n;j++) b[i][j] = a[i][j];
for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) a[i][j] = b[m-j+1][i];
sol(n,m);
for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) b[i][j] = a[i][j];
for(int i=1;i<=m;i++) for(int j=1;j<=n;j++) a[i][j] = b[n-j+1][i];
sol(m,n);
printf("%lld",ans);
}
/*
4 4
1 12 6 11
11 10 2 14
10 1 9 20
4 17 19 10
3 4
1 1 1 1
1 1 9 2
2 2 2 2
3 4
2 2 2 2
9 2 1 1
1 1 1 1
*/
Compilation message (stderr)
joioi.cpp: In function 'int main()':
joioi.cpp:46:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
46 | scanf("%lld%lld",&n,&m);
| ~~~~~^~~~~~~~~~~~~~~~~~
joioi.cpp:47:51: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
47 | for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) scanf("%lld",&a[i][j]);
| ~~~~~^~~~~~~~~~~~~~~~~
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