java杨辉三角递归实现

转载请注明出处：http://shuiguaiqq.iteye.com/blog/2065671

网上看到的几乎都是大同小异，而本人喜欢逻辑清晰的代码，忍不住动手写了下，代码如下：

public class YangHui {
    public static void main(String[] args) {
        int n = 9;
        displayYangHui(n);
    }

    public static void displayYangHui(int n) {
        for (int i = n - 1; i >= 0; i--) {
            for (int j = 0; j < i; j++) {
                System.out.print(" ");
            }
            showRow(getRow(n - i));
        }
    }

    private static void showRow(int[] row) {
        for (int i = 0; i < row.length; i++) {
            System.out.print(row[i] + " ");
        }
        System.out.println();
    }

    private static int[] getRow(int row) {
        if (row == 1) {
            return new int[] { 1 };
        }
        if (row == 2) {
            return new int[] { 1, 1 };
        }

        int[] result = new int[row];
        for (int i = 0; i < result.length; i++) {
            if (i == 0 || i == result.length - 1) {
                result[i] = 1;
            } else {
                result[i] = getRow(row - 1)[i - 1] + getRow(row - 1)[i];
            }
        }
        return result;
    }

}

 

评论

4 楼 wenchui 2016-03-18  

算法是有问题的，n超过11，就基本上算不出来了，层数多了，算不动了

3 楼 netkiller.github.com 2014-05-14  

都啥年代了，还杨辉三角

2 楼 shuiguaiQQ 2014-05-14  

zhang_xzhi_xjtu 写道

public class Yang4 {

    public static void main(String[] args) {
        compute(9);
    }

    public static void compute(int level) {
        for (int n = 0; n <= level; n++) {
            for (int c = 0; c <= n; c++) {
                System.out.print(compute(n, c) + "\t");
            }
            System.out.println();
        }
    }

    public static int compute(int n, int c) {
        if (c == n || c == 0)
            return 1;
        return compute(n - 1, c) + compute(n - 1, c - 1);
    }
}

好，不错

1 楼 zhang_xzhi_xjtu 2014-05-14  

public class Yang4 {

    public static void main(String[] args) {
        compute(9);
    }

    public static void compute(int level) {
        for (int n = 0; n <= level; n++) {
            for (int c = 0; c <= n; c++) {
                System.out.print(compute(n, c) + "\t");
            }
            System.out.println();
        }
    }

    public static int compute(int n, int c) {
        if (c == n || c == 0)
            return 1;
        return compute(n - 1, c) + compute(n - 1, c - 1);
    }
}