/**
 * Created by hcardena on 7/30/16.
 */
public class reverseWord {

  public static void main(String[] args) {
    String message = "find you will pain only go you recordings security the into if";
    //               "if into the security recordings you go only pain will you find"
    char[] m = message.toCharArray();

    // a b c. length = 3/2 = 1
    // a b. length = 2/2 = 1

    reverse(0, m.length, m);

    int start = 0;
    for (int i = 0; i < m.length; i++) {
      if (m[i] == ' ') {
        reverse(start, i, m);
        start = i+1;
      }
    }

    reverse(start, m.length, m);

    for (int i = 0; i < m.length; i++) {
      System.out.print(m[i]);
    }
    System.out.println();
  }

  private static void reverse(int start, int end, char[] m) {
    // end exclusive.
    int size = end-start;

    for (int i = 0; i < size/2; i++) {
      if (size % 2 != 0 && i == size/2) {
        break; // don't swap middle element in odd.
      }

      char tmp = m[start+i];
      m[start+i] = m[end-1-i];
      m[end-1-i] = tmp;
    }
  }
}