UVALive 5881 Unique Encryption Keys

Unique Encryption Keys

Time Limit: 30000MS Memory Limit: Unknown 64bit IO Format: %lld & %llu

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Description

The security of many ciphers strongly depends on the fact that the keys are unique and never re-used. This may be vitally important, since a relatively strong cipher may be broken if the same key is used to encrypt several different messages.

In this problem, we will try to detect repeating (duplicate) usage of keys. Given a sequence of keys used to encrypt messages, your task is to determine what keys have been used repeatedly in some specified period.

Input

The input contains several cipher descriptions. Each description starts with one line containing two integer numbers M and Q separated by a space. M(1M1000000) is the number of encrypted messages, Q is the number of queries (0Q1000000).

Each of the following M lines contains one number K_i(0K_i2³⁰) specifying the identifier of a key used to encrypt the i-th message. The next Q lines then contain one query each. Each query is specified by two integer numbers B_j and E_j, 1B_jE_jM, giving the interval of messages we want to check.

There is one empty line after each description. The input is terminated by a line containing two zeros in place of the numbers M and Q.

Output

For each query, print one line of output. The line should contain the string ``OK" if all keys used to encrypt messages between B_j and E_j (inclusive) are mutually different (that means, they have different identifiers). If some of the keys have been used repeatedly, print one identifier of any such key.

Print one empty line after each cipher description.

Sample Input

10 532349738411 32 64 103 72 65 2123122 41 50 0

Sample Output

3OK43OKOK1

#include <cstdlib>#include <cctype>#include <cstring>#include <cstdio>#include <cmath>#include <algorithm>#include <vector>#include <string>#include <iostream>#include <sstream>#include <map>#include <set>#include <queue>#include <stack>#include <fstream>#include <numeric>#include <iomanip>#include <bitset>#include <list>#include <stdexcept>#include <functional>#include <utility>#include <ctime>using namespace std;#define PB push_back#define MP make_pair#define CLR(vis) memset(vis,0,sizeof(vis))#define MST(vis,pos) memset(vis,pos,sizeof(vis))#define MAX3(a,b,c) max(a,max(b,c))#define MAX4(a,b,c,d) max(max(a,b),max(c,d))#define MIN3(a,b,c) min(a,min(b,c))#define MIN4(a,b,c,d) min(min(a,b),min(c,d))#define PI acos(-1.0)#define INF 0x7FFFFFFF#define LINF 1000000000000000000LL#define eps 1e-8typedef long long ll;typedef unsigned long long ull;const int maxn=1e6+100;int n,m;int a[maxn];int b[maxn];int main(){    while(scanf("%d%d",&n,&m)!=EOF)    {        if(!n && !m) break;        for(int i=0;i<n;i++)            scanf("%d",&a[i]);        map<int ,int > p;        p.clear();        CLR(b);        for(int i=n-1;i>=0;i--)        {            b[i]=INF;            if(i<n-1) b[i]=b[i+1];            if(p.find(a[i])!=p.end())                b[i]=min(b[i],p[a[i]]);            p[a[i]]=i;        }        int l,r;        for(int i=0;i<m;i++)        {            scanf("%d%d",&l,&r);            l--,r--;            if(b[l]<=r)                printf("%d\n",a[b[l]]);            else                printf("OK\n");        }        cout<<endl;    }    return 0;}