lower_bound

////////////////////////////////////////
//      2018/05/01 16:10:51
//      lower_bound

// returns an iterator to the first element greater than a certain value

#include <iostream>
#include <map>
#include <ctime>

using namespace std;

unsigned long int gener_rand(){
    unsigned long int random = (unsigned long int)(10000.0*rand() / (RAND_MAX + 1.0)) % 10;
    return random;
}
//--------------------------
int main(){
    unsigned long int ary[100];
    typedef map<int, unsigned long int > M;
    M m;

    // initialize all values to 0
    for (int i = 0; i < 100; i++){
        ary[i] = 0;
    }

    srand(time(0));

    // initialize ary[] with random values
    for (int i = 0; i < 100; i++){
        ary[i] = gener_rand();
    }

    for (int i = 0; i < 100; i++){
        if (i % 10 == 0 && i != 0){
            cout << endl;
        }
        cout << ary[i] << " ";
        // generate freaquances
        m[ary[i]] += 1;
    }
    cout << endl << endl;

    M::iterator it = m.begin();
    while (it != m.end()){
        cout << "number " << it->first
            << " occured " << it->second
            << " time(s)." << endl;
        it++;
    }
    cout << endl;
    m[12] = 123;
    m[15] = 234;
    m[18] = 345;

    // find leftmost node not less than _Keyval in mutable tree
    it = m.lower_bound(11);
    cout << "lower_bound(11) = " << it->first << endl;

    // find leftmost node greater than _Keyval in mutable tree
    it = m.upper_bound(11);
    cout << "upper_bound(11) = " << it->first << endl;
    return 0;
}


/*
OUTPUT:
    3 2 3 4 3 4 0 3 7 6
    4 1 2 4 5 1 9 2 2 9
    4 1 3 4 2 5 7 5 3 9
    0 1 0 2 8 1 4 2 4 4
    8 1 0 6 4 4 6 0 0 0
    5 6 9 1 4 0 0 8 8 1
    8 5 4 3 9 3 3 1 6 9
    9 2 8 0 0 3 7 4 3 8
    9 6 3 9 1 0 3 7 4 4
    1 4 6 8 8 5 6 1 3 6

    number 0 occured 12 time(s).
    number 1 occured 12 time(s).
    number 2 occured 8 time(s).
    number 3 occured 14 time(s).
    number 4 occured 17 time(s).
    number 5 occured 6 time(s).
    number 6 occured 9 time(s).
    number 7 occured 4 time(s).
    number 8 occured 9 time(s).
    number 9 occured 9 time(s).

    lower_bound(11) = 12
    upper_bound(11) = 12
*/