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Submission #199836

# Submission time Handle Problem Language Result Execution time Memory
199836 2020-02-03T15:30:48 Z ansol4328 Boat (APIO16_boat) C++14
9 / 100
 99 ms 4344 KB 
#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
const ll MOD=1e9+7;

int n, m[505][2];
ll inv[505], cnt[1005], dp[505][1005], sel[505];
vector<ll> lst;

ll get_pow(ll x, ll p)
{
    if(p==0) return 1;
    if(p==1) return x;
    ll ret=get_pow(x,p>>1);
    (ret*=ret)%=MOD;
    if(p&1) (ret*=x)%=MOD;
    return ret;
}

void init()
{
    ll fac=1;
    inv[0]=1;
    for(ll i=1 ; i<=n ; i++) (fac*=i)%=MOD;
    inv[n]=get_pow(fac,MOD-2);
    for(ll i=n ; i>=1 ; i--) inv[i-1]=(inv[i]*i)%MOD;
    for(int i=1 ; i<=n ; i++){
        if(m[i][0]==1) dp[i][1]=1;
        (dp[i][1]+=dp[i-1][1])%=MOD;
    }
    dp[1][m[1][0]]=1;
    for(int i=m[1][0]+1 ; i<=m[1][1] ; i++) dp[1][i]=(dp[1][i-1]+(lst[i-1]-lst[i-2]))%MOD;
    for(int i=m[1][1]+1 ; i<=(int)lst.size() ; i++) dp[1][i]=dp[1][i-1];
    for(int i=1 ; i<=(int)lst.size() ; i++){
        for(int j=1 ; j<=n ; j++){
            if(m[j][0]<i && i<=m[j][1]) cnt[i]++;
        }
    }
}

void calc_sel(ll L, ll K)
{
    ll lim=min(L,K);
    if(lim<2) return;
    for(ll i=2 ; i<=K ; i++){
        ll v1=1, v2=(L*(L-1))%MOD;
        ll val1, val2;
        sel[i]=(v2*(inv[2]))%MOD;
        for(ll j=3, x1=i-2, x2=L-2 ; j<=min(lim,i) ; j++, x1--, x2--){
            (v1*=x1)%=MOD;
            (v2*=x2)%=MOD;
            val1=(v1*inv[j-2])%MOD, val2=(v2*inv[j])%MOD;
            sel[i]+=(val1*val2)%MOD;
            sel[i]%=MOD;
        }
    }
}

int main()
{
    scanf("%d",&n);
    for(int i=1 ; i<=n ; i++){
        scanf("%d %d",&m[i][0],&m[i][1]);
        lst.push_back((ll)m[i][0]);
        lst.push_back((ll)m[i][1]);
    }
    //contraction
    sort(lst.begin(),lst.end());
    lst.erase(unique(lst.begin(),lst.end()),lst.end());
    for(int i=1 ; i<=n ; i++){
        m[i][0]=lower_bound(lst.begin(),lst.end(),(ll)m[i][0])-lst.begin()+1;
        m[i][1]=lower_bound(lst.begin(),lst.end(),(ll)m[i][1])-lst.begin()+1;
    }
    init();
    //solve
    for(int i=2 ; i<=(int)lst.size() ; i++){
        ll L=lst[i-1]-lst[i-2];
        if(cnt[i]>1) calc_sel(L,cnt[i]);
        for(int j=2 ; j<=n ; j++){
            (dp[j][i]+=dp[j-1][i])%=MOD;
            (dp[j][i]+=dp[j][i-1])%=MOD;
            dp[j][i]=(dp[j][i]-dp[j-1][i-1]+MOD)%MOD;
            if(i<m[j][0] || m[j][1]<i) continue;
            if(i==m[j][0] || L==1){
                (dp[j][i]+=dp[j-1][i-1]+1)%=MOD;
                continue;
            }
            ll val=(dp[j-1][i-1]*L+L)%MOD, c=1;
            for(int k=j-1 ; k>=1 ; k--){
                if(m[k][0]<i && i<=m[k][1]){
                    c++;
                    if(k!=1) (val+=sel[c]*dp[k-1][i-1])%=MOD;
                    else (val+=sel[c])%=MOD;
                }
            }
            (dp[j][i]+=val)%=MOD;
        }
    }
    printf("%lld",dp[n][(int)lst.size()]);
    return 0;
}

Compilation message

boat.cpp: In function 'int main()':
boat.cpp:62:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
boat.cpp:64:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d",&m[i][0],&m[i][1]);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 4216 KB Output is correct
2 Correct 12 ms 4088 KB Output is correct
3 Correct 13 ms 4216 KB Output is correct
4 Correct 13 ms 4216 KB Output is correct
5 Correct 13 ms 4216 KB Output is correct
6 Correct 12 ms 4216 KB Output is correct
7 Correct 13 ms 4344 KB Output is correct
8 Correct 12 ms 4216 KB Output is correct
9 Correct 12 ms 4216 KB Output is correct
10 Correct 12 ms 4216 KB Output is correct
11 Correct 12 ms 4344 KB Output is correct
12 Correct 13 ms 4344 KB Output is correct
13 Correct 12 ms 4216 KB Output is correct
14 Correct 13 ms 4216 KB Output is correct
15 Correct 13 ms 4216 KB Output is correct
16 Correct 8 ms 2680 KB Output is correct
17 Correct 7 ms 2680 KB Output is correct
18 Correct 8 ms 2680 KB Output is correct
19 Correct 7 ms 2680 KB Output is correct
20 Correct 7 ms 2680 KB Output is correct

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 4216 KB Output is correct
2 Correct 12 ms 4088 KB Output is correct
3 Correct 13 ms 4216 KB Output is correct
4 Correct 13 ms 4216 KB Output is correct
5 Correct 13 ms 4216 KB Output is correct
6 Correct 12 ms 4216 KB Output is correct
7 Correct 13 ms 4344 KB Output is correct
8 Correct 12 ms 4216 KB Output is correct
9 Correct 12 ms 4216 KB Output is correct
10 Correct 12 ms 4216 KB Output is correct
11 Correct 12 ms 4344 KB Output is correct
12 Correct 13 ms 4344 KB Output is correct
13 Correct 12 ms 4216 KB Output is correct
14 Correct 13 ms 4216 KB Output is correct
15 Correct 13 ms 4216 KB Output is correct
16 Correct 8 ms 2680 KB Output is correct
17 Correct 7 ms 2680 KB Output is correct
18 Correct 8 ms 2680 KB Output is correct
19 Correct 7 ms 2680 KB Output is correct
20 Correct 7 ms 2680 KB Output is correct
21 Incorrect 99 ms 4216 KB Output isn't correct
22 Halted 0 ms 0 KB -

Subtask #3
0 / 27.0

# Verdict Execution time Memory Grader output
1 Incorrect 8 ms 888 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 4216 KB Output is correct
2 Correct 12 ms 4088 KB Output is correct
3 Correct 13 ms 4216 KB Output is correct
4 Correct 13 ms 4216 KB Output is correct
5 Correct 13 ms 4216 KB Output is correct
6 Correct 12 ms 4216 KB Output is correct
7 Correct 13 ms 4344 KB Output is correct
8 Correct 12 ms 4216 KB Output is correct
9 Correct 12 ms 4216 KB Output is correct
10 Correct 12 ms 4216 KB Output is correct
11 Correct 12 ms 4344 KB Output is correct
12 Correct 13 ms 4344 KB Output is correct
13 Correct 12 ms 4216 KB Output is correct
14 Correct 13 ms 4216 KB Output is correct
15 Correct 13 ms 4216 KB Output is correct
16 Correct 8 ms 2680 KB Output is correct
17 Correct 7 ms 2680 KB Output is correct
18 Correct 8 ms 2680 KB Output is correct
19 Correct 7 ms 2680 KB Output is correct
20 Correct 7 ms 2680 KB Output is correct
21 Incorrect 99 ms 4216 KB Output isn't correct
22 Halted 0 ms 0 KB -