Submission #881329

#	Time	Username	Problem	Language	Result	Execution time	Memory
881329		tsumondai	Bitaro the Brave (JOI19_ho_t1)	C++14	100 / 100	171 ms	159340 KiB

joi2019_ho_t1

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

#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
#define __TIME  (1.0 * clock() / CLOCKS_PER_SEC)

typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;

const int N = 3e3 + 5;

const int oo = 1e9, mod = 1e9 + 7;

int n, m, preO[N][N], preI[N][N], res=0;
char s[N][N];

void process() {
	cin >> n >> m;
	foru(i, 1, n) {
		foru(j, 1, m) {
			cin >> s[i][j];
		}
	}

	foru(i, 1, n) {
		ford(j, m, 1) {
			preO[i][j] = preO[i][j + 1] + (s[i][j] == 'O');
		}
	}

	ford(i, n, 1) {
		foru(j, 1, m) {
			preI[i][j] = preI[i + 1][j] + (s[i][j] == 'I');
		}
	}

	foru(i,1,n-1) {
		foru(j,1,m-1) {
			if (s[i][j]=='J') res+=(preO[i][j] * preI[i][j]);
		}
	}

	cout << res;

	return;
}

signed main() {
	cin.tie(0)->sync_with_stdio(false);
	//freopen(".inp", "r", stdin);
	//freopen(".out", "w", stdout);
	process();
	cerr << "Time elapsed: " << __TIME << " s.\n";
	return 0;
}

/*
Xét các trường hợp đặc biệt
Kiểm tra lại input/output
Cố gắng trâu
Lật ngược bài toán
Keep calm and get VOI
Flow:

*/

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