2的模幂计算（UVA 11609）

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

public classMain {
	
	static final int MOD = 1000000007;
	
　　　　　//n * (C(n - 1, 0) + C(n - 1, 1) + ... + C(n - 1, n - 1)) == n * 2 ^ (n - 1) {模幂}
	long BigMod(int n) {
		long res = 1, temp = 2;
		while (n > 0) {
			if ((n & 1) != 0)
				res = (res * temp) % MOD;
			n >>= 1;
			temp = (temp * temp) % MOD;
		}
		return res;
	}
	
	void run() {
		int n, t;
		t = cin.nextInt();
		for (int Case = 1; Case <= t; Case++) {
			n = cin.nextInt();
			System.out.println("Case #" + Case + ": " + (n * BigMod(n - 1)) % MOD);
		}
	}               
	
	public static void main(String[] args) {
		Mainsolved = new Main();
		solved.run();
	}
	
//	static InputStream inputStream = System.in;
//	static InputReader cin = new InputReader(inputStream);
	
	Scannercin = 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; 
    } 

} 


公式：

　1.C(n, 1) + 2·C(n, 2) + 3·C(n, 3) + ... + n·C(n, n) = n2^n-1.

 　2.C(n, k) =

n!

k!(n-k)!