AC题解

#include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
 
int N;
bool ok[1000][1000];
 
ll solve() {
	ll ans = 0;
	vector<int> lst(N,N-1);
	vector<int> to_add[1000];
	for (int i = N-1; i >= 0; --i) {
		for (int j = i; j < N; ++j) to_add[j].clear();
		for (int k = 0; k < N; ++k) {
			if (ok[i][k] == 0) lst[k] = i-1;
			else to_add[lst[k]].push_back(k);
		}
		int sum_comb = 0;
		vector<int> lef(N,-1), rig(N,-1);
		for (int j = N-1; j >= i; --j) {
			for (int k: to_add[j]) {
				int l = k, r = k;
				auto c2 = [](int x) { return (x+1)*(x+2)/2; };
				if (k && lef[k-1] != -1) {
					l = lef[k-1];
					sum_comb -= c2(k-1-l);
				}
				if (k+1 < N && rig[k+1] != -1) {
					r = rig[k+1];
					sum_comb -= c2(r-k-1);
				}
				lef[r] = l, rig[l] = r;
				sum_comb += c2(r-l);
			}
			ans += sum_comb;
		}
	}
	return ans;
}
 
int main() {
	cin >> N;
	vector<vector<int>> pasture(N,vector<int>(N)); 
	for (vector<int>& a: pasture) 
		for (int& b: a) cin >> b;
 
	for (int i = 0; i < N; ++i) 
		for (int j = 0; j < N; ++j)
			ok[i][j] = pasture[i][j] >= 100;
	ll ans = solve();
 
	for (int i = 0; i < N; ++i) 
		for (int j = 0; j < N; ++j)
			ok[i][j] = pasture[i][j] > 100;
	ans -= solve();
 
	cout << ans << "\n";
}