Submission #549686

#	Time	Username	Problem	Language	Result	Execution time	Memory
549686		Pherokung	The Kingdom of JOIOI (JOI17_joioi)	C++14	0 / 100	205 ms	16104 KiB

joioi

#include<bits/stdc++.h>
using namespace std;
#define N 2005
#define F first
#define S second
int n,m,A[N][N],a[N][N],dp[N][N],ans=2e9;
typedef pair<int,int> pa;

pa cal(int n,int m,int v){
	memset(dp,0,sizeof dp);
	for(int i=0;i<=n;i++) dp[0][i] = 1;
	for(int i=0;i<=m;i++) dp[i][0] = 1;
	for(int i=1;i<=m;i++) for(int j=1;j<=n;j++) if(a[j][i] <= v && dp[j][i-1] && dp[j-1][i]) dp[j][i] = 1;
	int mx0=0,mx1=0,mn0=2e9,mn1=2e9;
	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++){
		if(!dp[i][j]) mx0 = max(mx0,a[i][j]), mn0 = min(mn0,a[i][j]);
		else mx1 = max(mx1,a[i][j]), mn1 = min(mn1,a[i][j]);
	}
	if(!dp[1][1]) return {0,2e9};
	if(dp[n][m]) return {2e9,0};
	if(mn1 > mn0) return {2e9,0};
//	printf(">> %d : %d %d %d %d\n",v,mx1,mn1,mx0,mn0);
	return {mx1-mn1,mx0-mn0};
}

int sol(int n,int m){
	int be = 1,ed = 1e9,ans=2e9;
	while(be < ed){
		int mid = (be+ed)/2;
		pa V = cal(n,m,mid);
		ans = min(ans,max(V.F,V.S));
//		printf("%d : %d %d\n",mid,V.F,V.S);
		if(V.F <= V.S) be = mid+1;
		else ed = mid;
	}
	return ans;
}

int main(){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) scanf("%d",&A[i][j]);
	
	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) a[i][j] = A[i][j];
	ans = min(ans,sol(n,m));

	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) a[n-i+1][j] = A[i][j];
	ans = min(ans,sol(n,m));
	
	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) a[m-j+1][n-i+1] = A[i][j];
	ans = min(ans,sol(m,n));
	
	for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) a[j][n-i+1] = A[i][j];
	ans = min(ans,sol(m,n));
//	for(int i=1;i<=m;i++){
//		for(int j=1;j<=n;j++) printf("%d ",a[i][j]);
//		printf("\n");
//	}
	printf("%d",ans);
}
/*
4 4
1 12 6 11
11 10 2 14
10 1 9 20
4 17 19 10
*/

Compilation message (stderr)

joioi.cpp: In function 'int main()':
joioi.cpp:40:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |  scanf("%d%d",&n,&m);
      |  ~~~~~^~~~~~~~~~~~~~
joioi.cpp:41:51: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |  for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) scanf("%d",&A[i][j]);
      |                                              ~~~~~^~~~~~~~~~~~~~~

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