Submission #1272785

#	Time	Username	Problem	Language	Result	Execution time	Memory
1272785		nthvn	Bitaro the Brave (JOI19_ho_t1)	C++20	100 / 100	232 ms	221168 KiB

joi2019_ho_t1

#include "bits/stdc++.h"
using namespace std;

#define fi first
#define se second
#define pii pair<int,int> 
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define pb push_back
#define ll long long
const int N = 3005;
int n,m;
string s[N];
int a[3][N][N], ps[3][N][N];

void build_ps(int a[][N], int ps[][N]){
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			ps[i][j] = ps[i-1][j]+ ps[i][j-1]-ps[i-1][j-1]+a[i][j];
		}
	}
}

int get(int ps[][N], int x, int y, int u, int v){
	return ps[u][v] - ps[x-1][v] - ps[u][y-1] + ps[x-1][y-1];
}

signed main(){
	ios_base::sync_with_stdio(NULL);
	cin.tie(NULL);
	if(fopen("TASK.INP", "r")){
		freopen("TASK.INP", "r", stdin);
		freopen("TASK.OUT", "w", stdout);
	}
	cin>>n>>m;
	for(int i=1;i<=n;i++) cin>>s[i], s[i]=' '+s[i];
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(s[i][j]=='J') a[0][i][j]=1;
			if(s[i][j]=='O') a[1][i][j]=1;
			if(s[i][j]=='I') a[2][i][j]=1;
		}
	}
	for(int i=0;i<=2;i++) build_ps(a[i],ps[i]);
	ll ans =0;
	for(int i=1;i<n;i++){
		for(int j=1;j<m;j++){
			if(!a[0][i][j]) continue;
			ll f = get(ps[1], i,j+1,i,m);
			ll g = get(ps[2], i+1,j,n,j);
			ans+= f*g;
		}
	}
	cout<<ans;
	
}

Compilation message (stderr)

joi2019_ho_t1.cpp: In function 'int main()':
joi2019_ho_t1.cpp:32:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |                 freopen("TASK.INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
joi2019_ho_t1.cpp:33:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |                 freopen("TASK.OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 30 / 30
• Subtask 3: 50 / 50