80-20

#!/bin/env python3
import sys

def readargs(args):
    files = []
    if len(args) == 1:
        files.append("-")
    else:
        for path in args[1:]:
            if path=="-":
                if "-" not in files:
                    files.append("-")
            else:
                files.append(path)
    for path in files:
        if path == "-":
            for line in sys.stdin:
                yield line
        else:
            with open(path):
                for line in path:
                    yield line

if __name__ == '__main__':
    sizes = []
    for line in readargs(sys.argv):
        if line.strip() == '':
            continue
        sizes.append(int(line))
    sizes.sort(reverse=True)
    total = sum(sizes)
    length = len(sizes)
    records = []
    for p in range(0, 101):
        ps = sum(sizes[:int(length*0.01*p)])/total*100
        records.append((p, ps, abs(100-ps-p)))
        print("{:3}% of the files use {:3.0f}% of the space".format(p, ps))
    print()
    p, ps, _ = sorted(records, key=lambda x: x[2])[0]
    print("{:3}% of the files use {:3.0f}% of the space".format(p, ps))