2010 年中兴面试题

输入两个整数n 和m，从数列1，2，3.......n 中随意取几个数,使其和等于m ,要求将其中所有的可能组合列出来.

0,1 背包问题

package search;

import java.util.Iterator;
import java.util.Stack;

public class Zte {
    private Stack<Integer> stack = new Stack<Integer>();

    public void findNM(int sum, int n) {
        if (n < 0 || sum < 0) {
            return;
        }
        if (sum > 0) {
            stack.push(n);
            findNM(sum - n, n - 1);
            stack.pop();
            findNM(sum, n - 1);
        } else {
            Iterator<Integer> it = stack.iterator();
            while (it.hasNext()) {
                System.out.print(it.next() + " ");
            }
            System.out.println();
        }
    }

    public static void main(String args[]) {
        Zte zte = new Zte();
        int n = 8; // 1,2,.....n
        int m = 10; // sum=m;
        if (n > m)
            n = m;
        zte.findNM(m, n);
    }
}