#!/usr/bin/env -S awk -f
# Usage: $0 file.abc > filtered_file.abc
BEGIN {
    OFS = FS = "\t"
}
{
    a=$1
    b=$2
    c=$3
    if (a > b) {
        tmp=a
        a=b
        b=tmp
    }
    if (!(b in graph[a])) {
        graph[a][b] = c
    } else {
        if (graph[a][b] < c) {
            graph[a][b] = c
        }
    }
}

END {
    for (a in graph) {
        for (b in graph[a]) {
            print a, b, graph[a][b]
        }
    }
}