set

问题 I have a hashmap that maps strings keys to hashsets values, and I want to remove a key from the hashmap when the hashmaps's hashset value is empty. I'm having trouble approaching this. Here's what I've tried but I'm very stuck: for(Map.Entry<String, HashSet<Integer>> entr : stringIDMap.entrySet()) { String key = entr.getKey(); if (stringIDMap.get(key).isEmpty()) { stringIDMap.remove(key); continue; } //few print statements... } 回答1: In order to avoid ConcurrentModificationException, you need

问题 I didn't realize the that Python set function actually separating string into individual characters. I wrote python function for Jaccard and used python intersection method. I passed two sets into this method and before passing the two sets into my jaccard function I use the set function on the setring. example: assume I have string NEW Fujifilm 16MP 5x Optical Zoom Point and Shoot CAMERA 2 7 screen.jpg i would call set(NEW Fujifilm 16MP 5x Optical Zoom Point and Shoot CAMERA 2 7 screen.jpg)

问题 Say I have a set D of multisets: D = { {d, g, o}, {a, e, t, t}, {a, m, t}, } Given a multiset M , like M = {a, a, m, t} I would like an algorithm f to give me all elements of D that are subsets (or more precisely, "submultisets") of M : f = {{a, m, t}} If we do only one such query, scanning over all elements of D (in O(#D) time) is clearly optimal. But if we want to answer many such queries for the same D and different M , we might be able to make it faster by preprocessing D into some

问题 Say I have a set D of multisets: D = { {d, g, o}, {a, e, t, t}, {a, m, t}, } Given a multiset M , like M = {a, a, m, t} I would like an algorithm f to give me all elements of D that are subsets (or more precisely, "submultisets") of M : f = {{a, m, t}} If we do only one such query, scanning over all elements of D (in O(#D) time) is clearly optimal. But if we want to answer many such queries for the same D and different M , we might be able to make it faster by preprocessing D into some

问题 Can anybody tell me how the internal implementation of set and dict is different in python? Do they use the same data structure in the background? ++ In theory, one can use dict to achieve set functionality. 回答1: In CPython, sets and dicts use the same basic data structure. Sets tune it slightly differently, but it is basically a hash table just like dictionaries. You can take a look at the implementation details in the C code: setobject.c and dictobject.c; the implementations are very close;

问题 Can anybody tell me how the internal implementation of set and dict is different in python? Do they use the same data structure in the background? ++ In theory, one can use dict to achieve set functionality. 回答1: In CPython, sets and dicts use the same basic data structure. Sets tune it slightly differently, but it is basically a hash table just like dictionaries. You can take a look at the implementation details in the C code: setobject.c and dictobject.c; the implementations are very close;

问题 I'm writing a divides-by-three function in Bash, and it won't let me set a variable to a number. fizzy.sh: #!/usr/bin/env sh div3() { return `$1 % 3 -eq 0` } d=div3 1 echo $d Example: $ ./fizzy.sh ./fizzy.sh: line 7: 1: command not found 回答1: Bash functions normally "return" values by printing them to standard output, where the caller can capture them using `func args ...` or $(func args ...) This makes functions work like external commands. The return statement, on the other hand, sets the

问题 Consider this snippet: class SomeClass(object): def __init__(self, someattribute="somevalue"): self.someattribute = someattribute def __eq__(self, other): return self.someattribute == other.someattribute def __ne__(self, other): return not self.__eq__(other) list_of_objects = [SomeClass()] print(SomeClass() in list_of_objects) set_of_objects = set([SomeClass()]) print(SomeClass() in set_of_objects) which evaluates to: True False Can anyone explain why the 'in' keyword has a different meaning

问题 I would like to set -x temporarily in my script and then return in to the original state. Is there a way to do it without starting new subshell? Something like echo_was_on=....... ... ... if $echo_was_on; then set -x; else set +x; fi 回答1: You can check the value of $- to see the current options; if it contains an x, it was set. You can check like so: old_setting=${-//[^x]/} ... if [[ -n "$old_setting" ]]; then set -x; else set +x; fi 回答2: Or in a case statement case $- in *x* ) echo "X is set

问题 I'm learning for the test from algorithms and I spotted problem that I cannot deal with for a few days. So I'm writing here for help. For a given two disjoint sets on plane : G={(x_1^G, y_1^G), (x_2^G, y_2^G), ..., (x_n^G, y_n^G)} D={(x_1^D, y_1^D), (x_2^D, y_2^D), ..., (x_n^D, y_n^D)} Where for every 1 <= i, j <= n we have y_i^D < y_j^G, so G is above D. Find an effective algorithm that counts the distance between them defined as: d(G,D) = min{ d(a,b): a \in G and b\in D }, where d(a,b) = |x