In the second part of the series papers, we set out to study the algorithmic efficiency of sparse sensing. Stemmed from co-prime sensing, we propose a generalized framework, termed Diophantine sensing, which utilizes generic Diophantine equation theory and higher-order sparse ruler to strengthen the sampling time, the degree of freedom (DoF), and the sampling sparsity, simultaneously.With a careful design of sampling spacings either in the temporal or spatial domain, co-prime sensing can reconstruct the autocorrelation of a sequence with significantly denser lags based on Bézout theorem. However, Bézout theorem also puts two practical constraints in the co-prime sensing framework. For frequency estimation, co-prime sampling needs Θ((M1 + M2)L) samples, which results in Θ(M1M2L) sampling time, where M1 and M2 are co-prime down-sampling rates and L is the number of snapshots required. As for Direction-of-arrival (DoA) estimation, the sensors cannot be arbitrarily sparse in co-prime arrays, where the least spacing has to be less than a half of wavelength.Resorting to higher-moment statistics, the proposed Diophantine framework presents two fundamental improvements. First, on frequency estimation, we prove that given arbitrarily large down-sampling rates, there exist sampling schemes where the number of samples needed is only proportional to the sum of DoF and the number of snapshots required, which implies a linear sampling time. Second, on Direction-of-arrival (DoA) estimation, we propose two generic array constructions such that given N sensors, the minimal distance between sensors can be as large as a polynomial of N , Θ(N q ), which indicates that an arbitrarily sparse array (with arbitrarily small mutual coupling) exists given sufficiently many sensors. In addition, asymptotically, the proposed array configurations produce the best known DoF bound compared to existing coarray designs.