Source of equal_range2a.cpp


  1: //equal_range2a.cpp

  3: #include <iostream>
  4: #include <vector>
  5: #include <algorithm>
  6: using namespace std;

  8: /**
  9: Tests if one integer has a smaller digit sum than another.
 10: Pre:\n i1 and i2 have been initialized and i1, i2 are both > 0.
 11: Post:\n Returns true if sum of the digits in i1 is < sum of digits
 12: in i2, and otherwise returns false.
 13: */
 14: bool hasSmallerDigitSum
 15: (
 16:     int i1, //in
 17:     int i2  //in
 18: )
 19: {
 20:     int digitSum1 = 0;
 21:     while (i1 != 0)
 22:     {
 23:         digitSum1 += i1 % 10;
 24:         i1 /= 10;
 25:     }

 27:     int digitSum2 = 0;
 28:     while (i2 != 0)
 29:     {
 30:         digitSum2 += i2 % 10;
 31:         i2 /= 10;
 32:     }
 33:     return digitSum1 < digitSum2;
 34: }

 36: int main()
 37: {
 38:     cout << "\nThis program illustrates the use of the STL equal_range() "
 39:         "algorithm (extended\nversion) to find the lower bound and upper "
 40:         "bound locations of a given target\nvalue in a vector of integers "
 41:         "ordered in the sense that one integer precedes\nanother if the "
 42:         "digit sum in the first is less than the digit sum in the second.";
 43:     cout << "\nPress Enter to continue ... ";  cin.ignore(80, '\n');

 45:     int a[] = {21, 13, 31, 40,  5, 51, 25, 52, 70,
 46:                 8, 62, 71, 45, 54, 55, 82, 38, 56,
 47:                65, 92, 39, 48, 75, 49, 59, 88};
 48:     vector<int> v(a, a+26);
 49:     cout << "\nHere are the contents of v:\n";
 50:     for (vector<int>::size_type i=0; i<v.size(); i++)
 51:         cout << v.at(i) << " ";
 52:     cout << "\nPress Enter to continue ... ";  cin.ignore(80, '\n');

 54:     pair<vector<int>::iterator, vector<int>::iterator> bounds;

 56:     bounds = equal_range(v.begin(), v.end(), 85, hasSmallerDigitSum);
 57:     if (bounds.first != v.end())
 58:         cout << "\nLower bound of 85 in v = " << *bounds.first;
 59:     if (bounds.first != v.end())
 60:         cout << "\nUpper bound of 85 in v = " << *bounds.second;
 61:     cout << "\nPress Enter to continue ... ";  cin.ignore(80, '\n');

 63:     bounds = equal_range(v.begin(), v.end(), 96, hasSmallerDigitSum);
 64:     if (bounds.first != v.end())
 65:         cout << "\nLower bound of 96 in v = " << *bounds.first;
 66:     if (bounds.first != v.end())
 67:         cout << "\nUpper bound of 96 in v = " << *bounds.second;
 68:     cout << "\nPress Enter to continue ... ";  cin.ignore(80, '\n');

 70:     bounds = equal_range(v.begin(), v.end(), 73, hasSmallerDigitSum);
 71:     if (bounds.first != v.end())
 72:         cout << "\nLower bound of 73 in v = " << *bounds.first;
 73:     if (bounds.first != v.end())
 74:         cout << "\nUpper bound of 73 in v = " << *bounds.second;
 75:     cout << "\nPress Enter to continue ... ";  cin.ignore(80, '\n');

 77:     bounds = equal_range(v.begin(), v.end(), 1, hasSmallerDigitSum);
 78:     if (bounds.first != v.end())
 79:         cout << "\nLower bound of 1 in v = " << *bounds.first;
 80:     if (bounds.first != v.end())
 81:         cout << "\nUpper bound of 1 in v = " << *bounds.second;
 82:     cout << "\nPress Enter to continue ... ";  cin.ignore(80, '\n');

 84:     bounds = equal_range(v.begin(), v.end(), 99, hasSmallerDigitSum);
 85:     if (bounds.first != v.end())
 86:         cout << "\nLower bound of 99 in v = " << *bounds.first;
 87:     if (bounds.first != v.end())
 88:         cout << "\nUpper bound of 99 in v = " << *bounds.second;
 89:     cout << "\nNote that both the lower and upper bound locations "
 90:         "\nof 99 are the end (one-past-the-last) vector position.";
 91:     cout << "\nPress Enter to continue ... ";  cin.ignore(80, '\n');
 92: }