Submission #425318

#	Time	Username	Problem	Language	Result	Execution time	Memory
425318		duality	Ruins 3 (JOI20_ruins3)	C++11	100 / 100	788 ms	6088 KiB

ruins3

#define DEBUG 0

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

#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}

// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
    public:
        template<typename T>
        _Debug& operator,(T val) {
            cout << val << endl;
            return *this;
        }
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif

// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back

// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;

// ---------- END OF TEMPLATE ----------
#define MOD 1000000007

int rem[1200];
int C[600][600],temp[600][600],ways[600];
int dp[1201][601];
int main() {
    int i;
    int N,A;
    scanf("%d",&N);
    for (i = 0; i < N; i++) scanf("%d",&A),rem[A-1] = 1;
    reverse(rem,rem+2*N);

    int j,k,c = 0;
    dp[0][0] = 1;
    for (i = 0; i < N; i++) {
        C[i][0] = 1;
        for (j = 1; j <= i; j++) C[i][j] = (C[i-1][j-1]+C[i-1][j]) % MOD;
    }
    for (i = 0; i < N; i++) {
        if (i == 0) temp[0][0] = 1;
        else {
            for (j = 0; j <= i; j++) {
                temp[i][j] = temp[i-1][j];
                if (j > 0) temp[i][j] = (temp[i][j]+(LLI) temp[i-1][j-1]*((MOD+1)/2)) % MOD;
                if (j < i-1) temp[i][j] = (temp[i][j]+(LLI) temp[i-1][j+1]*((MOD+1)/2)) % MOD;
            }
        }
        ways[i] = temp[i][0];
        for (j = 1; j <= i; j++) ways[i] = ((LLI) ways[i]*j) % MOD;
    }
    for (i = 0; i < 2*N; i++) {
        for (j = 0; j <= min(i+1,N); j++) {
            if (dp[i][j] == 0) continue;
            if (!rem[i]) dp[i+1][j] = (j <= c) ? 0:((LLI) dp[i][j]*(j-c)) % MOD;
            else {
                for (k = j; k <= min(i-c+1,N); k++) {
                    if (j == k) dp[i+1][k] += dp[i][j];
                    else {
                        LLI x = ((LLI) C[i-c-j][k-j-1]*ways[k-j-1]) % MOD;
                        x *= k-j+1,x %= MOD;
                        x *= (MOD+1)/2,x %= MOD;
                        dp[i+1][k] += (x*dp[i][j]) % MOD;
                    }
                    if (dp[i+1][k] >= MOD) dp[i+1][k] -= MOD;
                }
            }
        }
        c += !rem[i];
    }
    printf("%d\n",dp[2*N][N]);

    return 0;
}

Compilation message (stderr)

ruins3.cpp: In function 'int main()':
ruins3.cpp:65:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |     scanf("%d",&N);
      |     ~~~~~^~~~~~~~~
ruins3.cpp:66:34: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |     for (i = 0; i < N; i++) scanf("%d",&A),rem[A-1] = 1;
      |                             ~~~~~^~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 52 / 52
• Subtask 3: 42 / 42