2024/11/25 模拟赛总结

画展

没看数据范围想了半天DP。裸贪心。

滑冰场

1.建分层图跑最短路

2.启发式搜索

#include <bits/stdc++.h>
using namespace std;
#define int long long
constexpr int MAX_N = 2000;
constexpr int INF = LLONG_MAX;

int n, m;  // Grid dimensions
char grid[MAX_N][MAX_N]; 
int dist[MAX_N][MAX_N][5];  

pair<int, int> start;  

const int dx[5] = {0, 1, 0, -1, 0};
const int dy[5] = {0, 0, 1, 0, -1};

struct Node {
	int x, y, dir, turns;
};

queue<Node> q;

void bfs() {
	for (int i = 1; i <= 4; ++i) {
		dist[start.first][start.second][i] = 0;  
		q.push({start.first, start.second, i, 0}); 
	}
	
	while (!q.empty()) {
		Node curr = q.front();
		q.pop();
		
		int x = curr.x, y = curr.y, dir = curr.dir, turns = curr.turns;
		
		if (x < 1 || x > n || y < 1 || y > m) continue;
		
		if (grid[x][y] == '.') {
			int nx = x + dx[dir];
			int ny = y + dy[dir];
			
			if (dist[nx][ny][dir] > dist[x][y][dir] + 1) {
				dist[nx][ny][dir] = dist[x][y][dir] + 1;
				q.push({nx, ny, dir, turns + 1});
			}
		}
		else {
			for (int newDir = 1; newDir <= 4; ++newDir) {
				int nx = x + dx[newDir];
				int ny = y + dy[newDir];
				if (dist[nx][ny][newDir] > dist[x][y][dir] + 1 + turns) {
					dist[nx][ny][newDir] = dist[x][y][dir] + 1 + turns;
					q.push({nx, ny, newDir, turns + 1});
				}
			}
		}
	}
}

void solve() {
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= m; ++j) {
			cin >> grid[i][j];  
			if (grid[i][j] == 'G') {
				start = {i, j};  
			}
			for (int k = 1; k <= 4; ++k) {
				dist[i][j][k] = INF;  
			}
		}
	}
	
	bfs(); 

	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= m; ++j) {
			int res = min({dist[i][j][1], dist[i][j][2], dist[i][j][3], dist[i][j][4]});
			if (res == INF) cout << -1 << ' ';  
			else cout << res << ' ';  
		}
		cout << endl;
	}
}

signed main() {
	freopen("U.in","r",stdin);
	freopen("U.out","w",stdout);
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> n >> m;
	solve();
	
	return 0;
}

比赛

这种题还是跳了把...noip前不考虑

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e6 + 10;
int T, n, p;
int a[N];

int calculateAnswer(int n, int p, int a[]) {
	int ans = 0;
	sort(a + 1, a + n + 1);
	
	if (p == 1) {
		for (int i = 1; i <= n - 2; ++i) {
			if (a[i] + n >= a[n] + 1)
				ans += (n + i) * (n - i - 1) / 2 - (n - i - 1) * (i + 1);
		}
		for (int i = 1; i <= n - 2; ++i) {
			if (a[i] + n >= a[n - 1] + 1)
				ans += n - i - 2;
		}
		for (int i = 1; i <= n - 2; ++i) {
			if (a[i] + n >= a[n - 2] + 1)
				ans++;
		}
	} else if (p == 2) {
		for (int i = 1; i <= n - 2; ++i) {
			if (a[i] + n >= a[n] + 1)
				ans += (n + i) * (n - i - 1) / 2 - (n - i - 1) * (i + 1);
		}
		for (int i = 1; i <= n - 1; ++i) {
			if (a[i] + n >= a[n - 1] + 1)
				ans += n - i - 2;
		}
		for (int i = 1; i <= n - 1; ++i) {
			if (a[i] + n >= a[n - 1] + 1)
				ans++;
		}
	}
	return ans;
}

void solve() {
	cin >> n >> p;
	for (int i = 1; i <= n; ++i)
		cin >> a[i];
	cout << calculateAnswer(n, p, a) << endl;
}

signed main() {
	freopen("T.in", "r", stdin);
	freopen("T.out", "w", stdout);
	cin >> T;
	while (T--) solve();
	return 0;
}