Do all Cryptocurrencies uses same Public key Cryptography algorithm?
Not necessarily.

A cryptocoin can use whatever asymmetric algorithm they choose, and I'm sure some have tried different things, but ECDSA has a big advantage: public keys are generated from private keys.

With asymmetric algorithms like RSA, public and private keys are both generated together.  With ECDSA, you choose a random number (within certain limits), and that is your private key.  Now all you have to do is calculate the corresponding public key from your private key.  This makes new address generation quick, and computationally inexpensive.  It also allows for schemes such as BIP32 HD Wallets.

Also be aware that ECDSA can use the same algorithm using different elliptic curves.  Bitcoin uses secp256k1, but other curves exist as well.

In the end, it depends on the currency.  There is so much diversity nowadays, I doubt very much that they all use the same algorithm and curve.