Submission #444453

#	Time	Username	Problem	Language	Result	Execution time	Memory
444453		cpp219	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	60 ms	32016 KiB

kangaroo

#pragma GCC optimization O2
#pragma GCC optimization "unroll-loop"
#pragma target ("avx2")

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define fs first
#define sc second
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 2e3 + 9;
const ll Log2 = 20;
const ll mod = 1e9 + 7;

ll n,s,e,dp[N][N];

ll f(ll pos,ll g){
    if (pos == n + 1) return !g;
    if (dp[pos][g] != -1) return dp[pos][g];
    ll ans = 0;
    if (pos > e){
        if (g) ans = f(pos + 1,g - 1);
        ans = (ans + f(pos + 1,g + 1) * g * (g + 1))%mod;
    }
    else if (pos == e) ans = (f(pos + 1,g) + f(pos + 1,g + 1)*(g + 1))%mod;
    else if (pos > s){
        if (g) ans = f(pos + 1,g - 1);
        ans = (ans + f(pos + 1,g + 1) * (g + 1) * (g + 1))%mod;
    }
    else if (pos == s) ans = (f(pos + 1,g) + f(pos + 1,g + 1)*(g + 1))%mod;
    else if (pos < s){
        if (g) ans = f(pos + 1,g - 1);
        ans = (ans + f(pos + 1,g + 1) * (g + 2) * (g + 1))%mod;
    }
    return dp[pos][g] = ans;
}

int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
    #define task "tst"
    if (fopen(task".INP","r")){
        freopen(task".INP","r",stdin);
        //freopen(task".OUT","w",stdout);
    }
    cin>>n>>s>>e; memset(dp,-1,sizeof(dp));
    if (s > e) swap(s,e);
    cout<<f(2,0);
}

Compilation message (stderr)

kangaroo.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization O2
      | 
kangaroo.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
kangaroo.cpp:3: warning: ignoring '#pragma target ' [-Wunknown-pragmas]
    3 | #pragma target ("avx2")
      | 
kangaroo.cpp: In function 'int main()':
kangaroo.cpp:43:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |         freopen(task".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49