Submission #549724

#	Time	Username	Problem	Language	Result	Execution time	Memory
549724		Pherokung	The Kingdom of JOIOI (JOI17_joioi)	C++14	100 / 100	2734 ms	83192 KiB

joioi

#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]);
      |                                              ~~~~~^~~~~~~~~~~~~~~~~

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