Search a 2D Matrix

Write `search_matrix(matrix, target)` returning `True` if the value is present. Each row is sorted ascending, and the first value of a row is greater than the last value of the row above. search_matrix([[1,3,5,7],[10,11,16,20],[23,30,34,60]], 3) -> True search_matrix([[1,3,5,7],[10,11,16,20],[23,30,34,60]], 13) -> False Those two conditions together mean the matrix is one sorted sequence that happens to be stored in rows. Binary search over `[0, rows*cols)` and map each index back with `divmod(mid, cols)`. Searching for the row first and then within it also works and is a fine answer — say which you chose.