You are given a string s and q slicing queries. For each query, print the string cut by the same rules as Python's s[a:b:c].
Let n be the length of s; character positions count from 0 at the front up to n − 1.
A query has the form a:b or a:b:c. Each of a, b and c is an integer or empty. If c is missing or empty, the step c is 1.
When c is positive: if a is empty, start is 0; if b is empty, stop is n.
A given a gets n added if it is negative. If the result is less than 0 it becomes 0, and if it is greater than n it becomes n; that is start. b gives stop the same way.
Then join the characters at positions start, start + c, start + 2c, … in order, while the position is less than stop.
When c is negative: if a is empty, start is n − 1; if b is empty, stop is −1 (meaning character 0 is included).
A given a gets n added if it is negative. If the result is less than 0 it becomes −1, and if it is greater than n − 1 it becomes n − 1; that is start. b gives stop the same way.
Then join the characters at positions start, start + c, start + 2c, … in order, while the position is greater than stop.
The first line gives s, the second line gives q, and the next q lines give one query each.
For each query, print the cut string on one line. If it is empty, print -.
Input
s is a string of 1 to 200 lowercase English letters and digits. 1 ≤ q ≤ 400. When not empty, a, b and c are integers from -1,000 to 1,000, and c is not 0. Queries contain no spaces
When you run, these lines are fed to input()/stdin in order (the program doesn't stop to ask).
$ Ready
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In other languagesShow solutions by language · 8 languages
Only Python takes both a step and negative positions with s[a:b:c]. An empty part is None, so passing s[slice(None, None, -1)] lets Python pick the defaults according to the sign of the step. Other languages must build it: JS/TS slice(a, b) accepts negative positions but has no step (substring treats negatives as 0); Java substring(a, b), C# Substring(start, length) and Craykon Substring(start, count) throw when out of range. C++ substr(pos, len) forgives only a too-long length; a pos past the end is out_of_range. Trap ① with a negative step, an empty stop is −1, not 0. Using 0 drops character 0 from ::-1. That is also why filling the empty parts of s[a:b:c] with 0 or len(s) is wrong even in Python (s[0:8:-1] is empty). ② A negative position first gets n added and is clamped if still outside. With a negative step, below 0 clamps to −1, not 0, so -100::-1 is empty. ③ With a negative step, the upper limit of start is n − 1, not n. Allowing n reads outside the string (an error in Java, C# and Craykon, undefined behaviour in C). ④ Keep empty parts when splitting: Java split(":") drops trailing empty parts, so use split(":", -1). C strtok also merges :: into one. C++ std::optional and TS string | undefined can represent 'empty' separately from 0.
Pythonmain.py · 11 lines
import syslines = sys.stdin.read().split("\n")s = lines[0].strip()q = int(lines[1])out = []for line in lines[2:2 + q]: # 빈 칸은 None: s[None:None:-1]처럼 기본값을 Python이 정한다(0을 넣으면 안 된다) parts = [int(p) if p else None for p in line.strip().split(":")] out.append(s[slice(*parts)] or "-")print("\n".join(out))
JavaScriptmain.js · 29 lines
const lines = require("fs").readFileSync(0, "utf8").split("\n");const s = lines[0].trim();const n = s.length;const q = Number(lines[1]);// 음수 자리는 n을 더하고, 그래도 밖이면 [lo, hi] 안으로 당긴다function fit(x, lo, hi) { if (x < 0) x += n; return Math.min(Math.max(x, lo), hi);}function pySlice(text) { const [a, b, c] = text.trim().split(":"); // c가 없으면 undefined const step = c ? Number(c) : 1; let out = ""; if (step > 0) { const start = a ? fit(Number(a), 0, n) : 0; const stop = b ? fit(Number(b), 0, n) : n; for (let i = start; i < stop; i += step) out += s[i]; } else { // 거꾸로 갈 때 빈 끝은 0번 글자까지 넣는다는 뜻이라 -1로 둔다 const start = a ? fit(Number(a), -1, n - 1) : n - 1; const stop = b ? fit(Number(b), -1, n - 1) : -1; for (let i = start; i > stop; i += step) out += s[i]; } return out || "-";}console.log(lines.slice(2, 2 + q).map(pySlice).join("\n"));
TypeScriptmain.ts · 31 lines
import { readFileSync } from "node:fs";const lines: string[] = readFileSync(0, "utf8").split("\n");const s = lines[0].trim();const n = s.length;const q = Number(lines[1]);// 음수 자리는 n을 더하고, 그래도 밖이면 [lo, hi] 안으로 당긴다function fit(x: number, lo: number, hi: number): number { if (x < 0) x += n; return Math.min(Math.max(x, lo), hi);}function pySlice(text: string): string { const [a, b, c]: (string | undefined)[] = text.trim().split(":"); // c가 없으면 undefined const step = c ? Number(c) : 1; let out = ""; if (step > 0) { const start = a ? fit(Number(a), 0, n) : 0; const stop = b ? fit(Number(b), 0, n) : n; for (let i = start; i < stop; i += step) out += s[i]; } else { // 거꾸로 갈 때 빈 끝은 0번 글자까지 넣는다는 뜻이라 -1로 둔다 const start = a ? fit(Number(a), -1, n - 1) : n - 1; const stop = b ? fit(Number(b), -1, n - 1) : -1; for (let i = start; i > stop; i += step) out += s[i]; } return out || "-";}console.log(lines.slice(2, 2 + q).map(pySlice).join("\n"));
JavaMain.java · 42 lines
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;public class Main { static String s; static int n; // 음수 자리는 n을 더하고, 그래도 밖이면 [lo, hi] 안으로 당긴다 static int fit(int x, int lo, int hi) { if (x < 0) x += n; return Math.min(Math.max(x, lo), hi); } static String pySlice(String text) { String[] p = text.split(":", -1); // -1: 끝의 빈 칸도 버리지 않는다 boolean hasA = !p[0].isEmpty(), hasB = !p[1].isEmpty(); int step = p.length == 3 && !p[2].isEmpty() ? Integer.parseInt(p[2]) : 1; StringBuilder out = new StringBuilder(); if (step > 0) { int start = hasA ? fit(Integer.parseInt(p[0]), 0, n) : 0; int stop = hasB ? fit(Integer.parseInt(p[1]), 0, n) : n; for (int i = start; i < stop; i += step) out.append(s.charAt(i)); } else { // 거꾸로 갈 때 빈 끝은 0번 글자까지 넣는다는 뜻이라 -1로 둔다 int start = hasA ? fit(Integer.parseInt(p[0]), -1, n - 1) : n - 1; int stop = hasB ? fit(Integer.parseInt(p[1]), -1, n - 1) : -1; for (int i = start; i > stop; i += step) out.append(s.charAt(i)); } return out.length() > 0 ? out.toString() : "-"; } public static void main(String[] args) throws IOException { BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); s = in.readLine().trim(); n = s.length(); int q = Integer.parseInt(in.readLine().trim()); StringBuilder out = new StringBuilder(); for (int t = 0; t < q; t++) out.append(pySlice(in.readLine().trim())).append('\n'); System.out.print(out); }}
C#Main.cs · 47 lines
using System;using System.Text;class Program{ static string s = ""; static int n; // 음수 자리는 n을 더하고, 그래도 밖이면 [lo, hi] 안으로 당긴다 static int Fit(int x, int lo, int hi) { if (x < 0) x += n; return Math.Clamp(x, lo, hi); } static string PySlice(string text) { string[] p = text.Split(':'); // C#의 Split은 빈 칸도 남긴다 bool hasA = p[0] != "", hasB = p[1] != ""; int step = p.Length == 3 && p[2] != "" ? int.Parse(p[2]) : 1; var sb = new StringBuilder(); if (step > 0) { int start = hasA ? Fit(int.Parse(p[0]), 0, n) : 0; int stop = hasB ? Fit(int.Parse(p[1]), 0, n) : n; for (int i = start; i < stop; i += step) sb.Append(s[i]); } else { // 거꾸로 갈 때 빈 끝은 0번 글자까지 넣는다는 뜻이라 -1로 둔다 int start = hasA ? Fit(int.Parse(p[0]), -1, n - 1) : n - 1; int stop = hasB ? Fit(int.Parse(p[1]), -1, n - 1) : -1; for (int i = start; i > stop; i += step) sb.Append(s[i]); } return sb.Length > 0 ? sb.ToString() : "-"; } static void Main() { s = Console.ReadLine().Trim(); n = s.Length; int q = int.Parse(Console.ReadLine().Trim()); var output = new StringBuilder(); for (int t = 0; t < q; t++) output.Append(PySlice(Console.ReadLine().Trim())).Append('\n'); Console.Write(output); }}
C++main.cpp · 53 lines
#include <algorithm>#include <iostream>#include <optional>#include <string>#include <vector>std::string s;int n;// 음수 자리는 n을 더하고, 그래도 밖이면 [lo, hi] 안으로 당긴다int fit(int x, int lo, int hi) { if (x < 0) x += n; return std::clamp(x, lo, hi);}std::string pySlice(const std::string &text) { std::vector<std::optional<int>> p; // 빈 칸은 값이 없는 optional std::size_t from = 0; while (true) { std::size_t colon = text.find(':', from); std::string part = text.substr(from, colon == std::string::npos ? std::string::npos : colon - from); p.push_back(part.empty() ? std::nullopt : std::optional<int>(std::stoi(part))); if (colon == std::string::npos) break; from = colon + 1; } int step = p.size() == 3 && p[2] ? *p[2] : 1; std::string out; if (step > 0) { int start = p[0] ? fit(*p[0], 0, n) : 0; int stop = p[1] ? fit(*p[1], 0, n) : n; for (int i = start; i < stop; i += step) out += s[i]; } else { // 거꾸로 갈 때 빈 끝은 0번 글자까지 넣는다는 뜻이라 -1로 둔다 int start = p[0] ? fit(*p[0], -1, n - 1) : n - 1; int stop = p[1] ? fit(*p[1], -1, n - 1) : -1; for (int i = start; i > stop; i += step) out += s[i]; } return out.empty() ? "-" : out;}int main() { int q; std::cin >> s >> q; n = static_cast<int>(s.size()); std::string out; for (int t = 0; t < q; t++) { std::string line; std::cin >> line; out += pySlice(line) + '\n'; } std::cout << out; return 0;}
Cmain.c · 47 lines
#include <stdio.h>#include <stdlib.h>#include <string.h>static char s[256];static int n;/* 음수 자리는 n을 더하고, 그래도 밖이면 [lo, hi] 안으로 당긴다 */static int fit(int x, int lo, int hi) { if (x < 0) x += n; return x < lo ? lo : x > hi ? hi : x;}int main(void) { char line[64]; int q; scanf("%255s %d", s, &q); n = (int)strlen(s); for (int t = 0; t < q; t++) { scanf("%63s", line); /* ':'로 칸을 나눈다. strtok는 빈 칸을 건너뛰어서 직접 나눈다 */ char *part[3] = {line, NULL, NULL}; int k = 1; for (char *c = line; *c; c++) if (*c == ':') { *c = '\0'; part[k++] = c + 1; } int hasA = part[0][0] != '\0', hasB = part[1][0] != '\0'; int step = k == 3 && part[2][0] != '\0' ? atoi(part[2]) : 1; char out[256]; int len = 0; if (step > 0) { int start = hasA ? fit(atoi(part[0]), 0, n) : 0; int stop = hasB ? fit(atoi(part[1]), 0, n) : n; for (int i = start; i < stop; i += step) out[len++] = s[i]; } else { /* 거꾸로 갈 때 빈 끝은 0번 글자까지 넣는다는 뜻이라 -1로 둔다 */ int start = hasA ? fit(atoi(part[0]), -1, n - 1) : n - 1; int stop = hasB ? fit(atoi(part[1]), -1, n - 1) : -1; for (int i = start; i > stop; i += step) out[len++] = s[i]; } out[len] = '\0'; puts(len > 0 ? out : "-"); } return 0;}
Craykonmain.cray · 64 lines
s = Console.ReadLine().Trim();n = s.Length;q = Console.ReadLine().ToNumber();// 음수 자리는 n을 더하고, 그래도 밖이면 [lo, hi] 안으로 당긴다맞추기(x, lo, hi){ if (x < 0) { x = x + n; } return Mathf.Min(Mathf.Max(x, lo), hi);}for (t = 0; t < q; t++){ p = Console.ReadLine().Trim().Split(":"); 걸음 = 1; if (p.Count == 3 && p[2] != "") { 걸음 = p[2].ToNumber(); } 답 = ""; if (걸음 > 0) { 시작 = 0; 끝 = n; if (p[0] != "") { 시작 = 맞추기(p[0].ToNumber(), 0, n); } if (p[1] != "") { 끝 = 맞추기(p[1].ToNumber(), 0, n); } for (k = 시작; k < 끝; k = k + 걸음) { 답 = 답 + s[k]; } } else { // 거꾸로 갈 때 빈 끝은 0번 글자까지 넣는다는 뜻이라 -1로 둔다 시작 = n - 1; 끝 = -1; if (p[0] != "") { 시작 = 맞추기(p[0].ToNumber(), -1, n - 1); } if (p[1] != "") { 끝 = 맞추기(p[1].ToNumber(), -1, n - 1); } for (k = 시작; k > 끝; k = k + 걸음) { 답 = 답 + s[k]; } } if (답 == "") { 답 = "-"; } Console.WriteLine(답);}