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Submission #24029

# Submission time Handle Problem Language Result Execution time Memory
24029 2017-05-29T14:05:58 Z Extazy Three Friends (BOI14_friends) C++14
100 / 100
 196 ms 77800 KB 
#include <bits/stdc++.h>
#define endl '\n'

using namespace std;

const int N = 1<<21;
const unsigned long long B1 = 139, B2 = 137, MOD = (1e9) + 696969;

struct rolling_hash {
    unsigned long long h1,h2;
    void initialize() {
        h1=0;
        h2=0;
    }
    void append(char a) {
        h1*=B1;h1+=a-'A'+1;h1%=MOD;
        h2*=B2;h2+=a-'A'+1;h2%=MOD;
    }
    bool operator ==(const rolling_hash &a) const {
        return h1==a.h1 && h2==a.h2;
    }
    bool operator <(const rolling_hash &a) const {
        return ((h1==a.h1) ? h2<a.h2 : h1<a.h2);
    }
};

int tests,current_case;
int n;
unsigned long long pw1[N],pw2[N];
rolling_hash ph[N];
int ans[N],sz;
rolling_hash h1,h2;
char a[N];
rolling_hash h;
int cnt;
set < rolling_hash > s;

void message(int current_case) {
    //cerr<<"Case "<<current_case<<" solved!"<<endl;
    fprintf(stderr, "Case %d solved!\n", current_case);
}

rolling_hash merge_hashes(rolling_hash a, rolling_hash b, int length) {
    a.h1*=pw1[length];
    a.h1+=b.h1;
    a.h1%=MOD;
    a.h2*=pw2[length];
    a.h2+=b.h2;
    a.h2%=MOD;
    return a;
}

rolling_hash get_hash(int l, int r) {
    rolling_hash hl=ph[l-1],hr=ph[r];
    hl.h1*=pw1[r-l+1];
    hl.h1%=MOD;
    hl.h2*=pw2[r-l+1];
    hl.h2%=MOD;
    hr.h1-=hl.h1;
    hr.h1+=MOD;
    hr.h1%=MOD;
    hr.h2-=hl.h2;
    hr.h2+=MOD;
    hr.h2%=MOD;
    return hr;
}

int main() {
    //ios_base::sync_with_stdio(false);
    //cin.tie(NULL);
    int i;

    pw1[0]=1;
    pw2[0]=1;
    for(i=1;i<N;i++) pw1[i]=pw1[i-1]*B1%MOD,pw2[i]=pw2[i-1]*B2%MOD;

    tests=1;
    //scanf("%d", &tests);
    //cin>>tests;
    for(current_case=1;current_case<=tests;current_case++) {
        s.clear();
        scanf("%d", &n);
        scanf("%s", a+1);
        h.initialize();
        ph[0]=h;
        for(i=1;i<=n;i++) h.append(a[i]),ph[i]=h;
        if(!(n&1)){
            printf("NOT POSSIBLE\n");
            goto MESSAGE;
        }
        sz=0;
        for(i=1;i<=n;i++) {
            if(i>n/2) h1=get_hash(1,n/2);
            else h1=merge_hashes(get_hash(1,i-1),get_hash(i+1,n/2+1),n/2+1-(i+1)+1);
            if(i<n-n/2+1) h2=get_hash(n-n/2+1,n);
            else h2=merge_hashes(get_hash(n-n/2,i-1),get_hash(i+1,n),n-i);
            if(h1==h2) ans[++sz]=i,s.insert(h1);
        }
        sz=(int)(s.size());
        if(sz==0) {
            printf("NOT POSSIBLE\n");
            goto MESSAGE;
        }
        else if(sz>1) {
            printf("NOT UNIQUE\n");
            goto MESSAGE;
        }
        cnt=0;
        for(i=1;cnt<n/2;i++) {
            if(i==ans[1]) continue;
            ++cnt;
            printf("%c", a[i]);
        }
        printf("\n");

        MESSAGE:
        message(current_case);
    }

    return 0;
}

Compilation message

friends.cpp: In function 'int main()':
friends.cpp:82:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &n);
                        ^
friends.cpp:83:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%s", a+1);
                         ^

Subtask #1
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 77800 KB Output is correct
2 Correct 16 ms 77800 KB Output is correct
3 Correct 13 ms 77800 KB Output is correct
4 Correct 13 ms 77800 KB Output is correct
5 Correct 13 ms 77800 KB Output is correct
6 Correct 9 ms 77800 KB Output is correct
7 Correct 23 ms 77800 KB Output is correct
8 Correct 19 ms 77800 KB Output is correct
9 Correct 23 ms 77800 KB Output is correct
10 Correct 19 ms 77800 KB Output is correct
11 Correct 13 ms 77800 KB Output is correct
12 Correct 9 ms 77800 KB Output is correct
13 Correct 13 ms 77800 KB Output is correct
14 Correct 6 ms 77800 KB Output is correct
15 Correct 13 ms 77800 KB Output is correct
16 Correct 13 ms 77800 KB Output is correct
17 Correct 16 ms 77800 KB Output is correct
18 Correct 13 ms 77800 KB Output is correct
19 Correct 13 ms 77800 KB Output is correct
20 Correct 13 ms 77800 KB Output is correct
21 Correct 13 ms 77800 KB Output is correct
22 Correct 6 ms 77800 KB Output is correct
23 Correct 13 ms 77800 KB Output is correct
24 Correct 19 ms 77800 KB Output is correct
25 Correct 13 ms 77800 KB Output is correct
26 Correct 16 ms 77800 KB Output is correct
27 Correct 9 ms 77800 KB Output is correct
28 Correct 9 ms 77800 KB Output is correct
29 Correct 6 ms 77800 KB Output is correct
30 Correct 16 ms 77800 KB Output is correct
31 Correct 9 ms 77800 KB Output is correct
32 Correct 16 ms 77800 KB Output is correct
33 Correct 13 ms 77800 KB Output is correct
34 Correct 6 ms 77800 KB Output is correct
35 Correct 9 ms 77800 KB Output is correct
36 Correct 13 ms 77800 KB Output is correct
37 Correct 16 ms 77800 KB Output is correct
38 Correct 6 ms 77800 KB Output is correct
39 Correct 9 ms 77800 KB Output is correct
40 Correct 13 ms 77800 KB Output is correct
41 Correct 16 ms 77800 KB Output is correct
42 Correct 19 ms 77800 KB Output is correct
43 Correct 13 ms 77800 KB Output is correct
44 Correct 6 ms 77800 KB Output is correct
45 Correct 9 ms 77800 KB Output is correct
46 Correct 16 ms 77800 KB Output is correct
47 Correct 16 ms 77800 KB Output is correct
48 Correct 6 ms 77800 KB Output is correct
49 Correct 9 ms 77800 KB Output is correct
50 Correct 9 ms 77800 KB Output is correct
51 Correct 13 ms 77800 KB Output is correct
52 Correct 9 ms 77800 KB Output is correct
53 Correct 13 ms 77800 KB Output is correct
54 Correct 19 ms 77800 KB Output is correct

Subtask #2
65.0 / 65.0

# Verdict Execution time Memory Grader output
1 Correct 139 ms 77800 KB Output is correct
2 Correct 149 ms 77800 KB Output is correct
3 Correct 163 ms 77800 KB Output is correct
4 Correct 136 ms 77800 KB Output is correct
5 Correct 196 ms 77800 KB Output is correct
6 Correct 26 ms 77800 KB Output is correct
7 Correct 186 ms 77800 KB Output is correct
8 Correct 103 ms 77800 KB Output is correct
9 Correct 149 ms 77800 KB Output is correct
10 Correct 146 ms 77800 KB Output is correct
11 Correct 73 ms 77800 KB Output is correct
12 Correct 13 ms 77800 KB Output is correct
13 Correct 13 ms 77800 KB Output is correct
14 Correct 9 ms 77800 KB Output is correct
15 Correct 9 ms 77800 KB Output is correct
16 Correct 13 ms 77800 KB Output is correct
17 Correct 16 ms 77800 KB Output is correct
18 Correct 19 ms 77800 KB Output is correct
19 Correct 16 ms 77800 KB Output is correct
20 Correct 9 ms 77800 KB Output is correct
21 Correct 9 ms 77800 KB Output is correct
22 Correct 6 ms 77800 KB Output is correct
23 Correct 3 ms 77800 KB Output is correct
24 Correct 9 ms 77800 KB Output is correct
25 Correct 19 ms 77800 KB Output is correct
26 Correct 23 ms 77800 KB Output is correct
27 Correct 9 ms 77800 KB Output is correct
28 Correct 13 ms 77800 KB Output is correct
29 Correct 13 ms 77800 KB Output is correct
30 Correct 6 ms 77800 KB Output is correct
31 Correct 6 ms 77800 KB Output is correct
32 Correct 23 ms 77800 KB Output is correct
33 Correct 9 ms 77800 KB Output is correct
34 Correct 9 ms 77800 KB Output is correct
35 Correct 16 ms 77800 KB Output is correct
36 Correct 9 ms 77800 KB Output is correct
37 Correct 13 ms 77800 KB Output is correct
38 Correct 13 ms 77800 KB Output is correct
39 Correct 6 ms 77800 KB Output is correct
40 Correct 9 ms 77800 KB Output is correct
41 Correct 19 ms 77800 KB Output is correct
42 Correct 13 ms 77800 KB Output is correct
43 Correct 9 ms 77800 KB Output is correct
44 Correct 9 ms 77800 KB Output is correct
45 Correct 23 ms 77800 KB Output is correct
46 Correct 16 ms 77800 KB Output is correct
47 Correct 19 ms 77800 KB Output is correct
48 Correct 16 ms 77800 KB Output is correct
49 Correct 19 ms 77800 KB Output is correct
50 Correct 16 ms 77800 KB Output is correct
51 Correct 16 ms 77800 KB Output is correct
52 Correct 16 ms 77800 KB Output is correct
53 Correct 3 ms 77800 KB Output is correct
54 Correct 16 ms 77800 KB Output is correct