Submission #43984

#	Time	Username	Problem	Language	Result	Execution time	Memory
43984		ruhanhabib39	Tents (JOI18_tents)	C++17	100 / 100	122 ms	71340 KiB

tents

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

const int MX = 3000;
const long long MOD = 1e9 + 7;

long long dp[MX + 10][MX + 10];

long long calc(long long H, long long W) {
   for(int w = 0; w <= W; w++) {
      dp[0][w] = 1;
   }
   for(int h = 0; h <= H; h++) {
      dp[h][0] = 1;
   }
   for(int h = 1; h <= H; h++) {
      for(int w = 1; w <= W; w++) {
         long long zero = dp[h-1][w];
         long long one = 4*w * dp[h-1][w-1] % MOD;
         long long two_horiz = 0, two_vert = 0;
         if(w >= 2) two_horiz = w*(w - 1) / 2 * dp[h-1][w-2] % MOD;
         if(h >= 2) two_vert = w * (h - 1) * dp[h-2][w-1] % MOD;
         dp[h][w] = (zero + one + two_horiz + two_vert) % MOD;
      }
   }
   return dp[H][W];
}

int main() {
   long long H, W; cin >> H >> W;
   cout << (calc(H, W) + MOD - 1) % MOD << endl;
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52