Forty Gigabytes Of Zeroes

A road network has $V = 100{,}000$ intersections and $E = 200{,}000$ two-way roads. A teammate wants int adj[100000][100000] because an edge lookup is then a single array read, and the container has 4 GB of RAM.

Assume a 4-byte int and count 1 GB = 10^9 bytes. How much does each representation need?