类似冒泡排序法（ZOJ 1730）

http://blog.csdn.net/yzl_rex/article/details/7391777

如果所有人是线性排列,那我们的工作就是类似冒泡程序做的工作:1,2,3,4,5变为5,4,3,2,1 ,耗时n(n-1)/2
 但是出现了环,也就是说1,2,3,4,5变为3,2,1,5,4也可满足条件
我们可以把这个环等分成两个部分（四部分不行了，圆的头与尾接不上了） ,每个部分看成是线性的,再把它们花的时间加起来.
 当n是偶数时, 每份人数n/2 ,即 2*(n/2 )*(n/2 -1)/2;
 当n是奇数时,两份的人数分别是n/2和n/2+1,即(n/2)*(n/2 -1)/2 + (n/2 +1)*(n/2)/2

import java.io.*;
import java.util.*;
import java.math.*;

public classMain {
	
	int t, n;
	
	void run() {
		t = cin.nextInt();
		while (t-- > 0) {
			n = cin.nextInt();
			if ((n & 1) > 0) 
				System.out.println(n / 2 * (n / 2 - 1) / 2 + n / 2 * (n / 2 + 1) / 2);
			else 
				System.out.println(2 * n / 2 * (n / 2 - 1) / 2);
		}
	}               
	
	public static void main(String[] args) {
		Mainsolved = new Main();
		solved.run();
	}
	
	static InputStreaminputStream = System.in;
	static InputReadercin = new InputReader(inputStream);
	
//	Scanner cin = new Scanner(new BufferedInputStream(System.in));
	
}


classInputReader { 

    private InputStreamstream; 
    private byte[] buf = new byte[1024]; 
    private int curChar; 
    private int numChars; 

    public InputReader(InputStreamstream) { 
        this.stream = stream; 
    } 

    public int read() { 
        if (numChars == -1) 
            return -1; 
            //throw new InputMismatchException(); 
        if (curChar >= numChars) { 
            curChar = 0; 
            try { 
                numChars = stream.read(buf); 
            } catch (IOExceptione) { 
                throw new InputMismatchException(); 
            } 
            if (numChars <= 0) 
                return -1; 
        } 
        return buf[curChar++]; 
    } 

    public int nextInt() { 
        int c = read(); 
        if (c == -1) 
            return -1; 
        while (isSpaceChar(c)) 
            c = read(); 
        int sgn = 1; 
        if (c == '-') { 
            sgn = -1; 
            c = read(); 
        } 
        int res = 0; 
        do { 
            if (c < '0' || c > '9') 
                throw new InputMismatchException(); 
            res *= 10; 
            res += c - '0'; 
            c = read(); 
        } while (!isSpaceChar(c)); 
        return res * sgn; 
    } 
     
    public Stringnext() {   
        StringBuilderstr = new StringBuilder();   
        int ch;   
        while (isSpaceChar(ch = read()));   
        if (ch == -1)   
            return null;   
        do {   
            str.appendCodePoint(ch);   
        } while (!isSpaceChar(ch = read()));   
        return str.toString();   
    }  
     
    public static boolean isSpaceChar(int c) { 
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; 
    } 

    public char nextCharacter() { 
        int c = read(); 
        while (isSpaceChar(c)) 
            c = read(); 
        return (char) c; 
    } 

}