整数拆分

 int caculate(int m){
        int[][] a = new int[m+1][m+1];
        for (int i = 1; i <= m; i++)
            for (int j = 1; j <= m; j++) {
                if (i == 1 || j == 1)
                    a[i][j] = 1;
                else {
                    if (i == j)
                        a[i][j] = a[i][j - 1] + 1;
                    else if (i < j) {
                        a[i][j] = a[i][i];
                    } else {
                        a[i][j] = a[i - j][j] + a[i][j - 1];
                    }
                }
            }
        return a[m][m];
    }