Suppose we need to store a table of distances between cities, as found in a road atlas. One obvious approach would be to use a square array distances, where distances[i][j] is the distance between...

Suppose we need to store a table of distances between cities, as found in a road atlas. One obvious approach would be to use a square array distances, where distances[i][j] is the distance between city i and city j. Explain how to use a ragged array to cut the amount of memory needed for this data structure roughly in half.