Submission #1027830

#	Time	Username	Problem	Language	Result	Execution time	Memory
1027830		mansur	Flooding Wall (BOI24_wall)	C++17	25 / 100	447 ms	1048576 KiB

Main

#include<bits/stdc++.h>

using namespace std;

#define rall(s) s.rbegin(), s.rend()
#define all(s) s.begin(), s.end()
#define sz(s) (int)s.size()
#define s second
#define f first

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

const int N = 1e6, mod = 1e9 + 7;
const int inf = 1e9;

int n;
int a[N][2];

void f() {
	int ans = 0;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j < i; j++) {
		    for (int k = i + 1; k <= n; k++) {
		  		for (int x = 0; x < 2; x++) {
					for (int y = 0; y < 2; y++) {
						int v = 1;
						for (int s = 1; s <= n; s++) {
							if (s == i || s == j || s == k) continue;
							int cnt = 0;
							if (s < i) {
								if (s < j) {
									if (a[s][1] < a[j][x]) cnt = 2;
									else if (a[s][0] < a[j][x]) cnt = 1;
									else cnt = 0;
								}else {
									if (a[s][1] <= a[j][x]) cnt = 2;
									else if (a[s][0] <= a[j][x]) cnt = 1;
									else cnt = 0;
								}
							}else {
								if (s > k) {
									if (a[s][1] < a[k][y]) cnt = 2;
									else if (a[s][0] < a[k][y]) cnt = 1;
									else cnt = 0;
								}else {
									if (a[s][1] <= a[k][y]) cnt = 2;
									else if (a[s][0] <= a[k][y]) cnt = 1;
									else cnt = 0;
								}
							}
							v = (v * cnt) % mod;
						}
						if (!v) continue;
						for (int z = 0; z < 2; z++) {
							if (a[i][z] > a[j][x] || a[i][z] > a[k][y]) continue;
							ans = (ans + ((min(a[j][x], a[k][y]) - a[i][z]) * 1ll * v) % mod) % mod;
						}
		  			}
			  	}
		    }
		}	
	}
	cout << ans;	
	exit(0);
}

void solve() {
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> a[i][0];
	for (int i = 1; i <= n; i++) cin >> a[i][1];
	for (int i = 1; i <= n; i++) {
		if (a[i][1] < a[i][0]) swap(a[i][1], a[i][0]);	
	}
	if (n <= 100) f();
	int dp[n + 1][1001], cnt[n + 1][1001];
	memset(dp, 0, sizeof(dp));
	memset(cnt, 0, sizeof(cnt));
	cnt[1][0] = 1;
	for (int i = 1; i < n; i++) {
		for (int x = 0; x <= 1000; x++) {
		    int v = a[i][0];
		    if (v < x) {
		    	int val = (cnt[i][x] * 1ll * (x - v)) % mod;
		    	dp[i + 1][x] = (dp[i + 1][x] + (dp[i][x] + val) % mod) % mod;
		    	cnt[i + 1][x] = (cnt[i + 1][x] + cnt[i][x]) % mod;
		    }else {
		    	cnt[i + 1][v] = (cnt[i + 1][v] + cnt[i][x]) % mod;
		    	dp[i + 1][v] = (dp[i + 1][v] + dp[i][x]) % mod;
		    }
		    v = a[i][1];
		    if (v < x) {
		    	int val = (cnt[i][x] * 1ll * (x - v)) % mod;
		    	dp[i + 1][x] = (dp[i + 1][x] + (dp[i][x] + val) % mod) % mod;
		    	cnt[i + 1][x] = (cnt[i + 1][x] + cnt[i][x]) % mod;
		    }else {
		    	cnt[i + 1][v] = (cnt[i + 1][v] + cnt[i][x]) % mod;
				dp[i + 1][v] = (dp[i + 1][v] + dp[i][x]) % mod;
			}
		}
	}
	int pd[n + 1][1001], ct[n + 1][1001];
	memset(pd, 0, sizeof(pd));
	memset(ct, 0, sizeof(ct));
	ct[n][0] = 1;
	for (int i = n; i > 1; i--) {
		for (int x = 0; x <= 1000; x++) {
		    int v = a[i][0];
		    if (v < x) {
		    	int val = (ct[i][x] * 1ll * (x - v)) % mod;
		    	pd[i - 1][x] = (pd[i - 1][x] + (pd[i][x] + val) % mod) % mod;
		    	ct[i - 1][x] = (ct[i - 1][x] + ct[i][x]) % mod;
		    }else {
		    	ct[i - 1][v] = (ct[i - 1][v] + ct[i][x]) % mod;
		    	pd[i - 1][v] = (pd[i - 1][v] + pd[i][x]) % mod;
		    }
		    v = a[i][1];
		    if (v < x) {
		    	int val = (ct[i][x] * 1ll * (x - v)) % mod;
		    	pd[i - 1][x] = (pd[i - 1][x] + (pd[i][x] + val) % mod) % mod;
		    	ct[i - 1][x] = (ct[i - 1][x] + ct[i][x]) % mod;
		    }else {
		    	ct[i - 1][v] = (ct[i - 1][v] + ct[i][x]) % mod;
				pd[i - 1][v] = (pd[i - 1][v] + pd[i][x]) % mod;
			}
		}
	}
	int ans = 0;
	for (int i = 1; i <= n; i++) {
	 	int v = a[i][0];
	 	for (int x = 0; x <= v; x++) {
	 		ans = (ans + dp[i][x]) % mod;
	 		if (x < v) ans = (ans + pd[i][x]) % mod;
	 	}
	 	v = a[i][1];
	 	for (int x = 0; x <= v; x++) {
	 		ans = (ans + dp[i][x]) % mod;
	 		if (x < v) ans = (ans + pd[i][x]) % mod;
	 	}
	}
	cout << ans;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	solve();
}

• Subtask 1: 8 / 8
• Subtask 2: 17 / 17
• Subtask 3: 0 / 19
• Subtask 4: 0 / 14
• Subtask 5: 0 / 12
• Subtask 6: 0 / 30