Question

String str[]={"-123","89","-10","456"};
str是一个字符串数组，每个字符串都为整数格式，您必须在O(n log n)时间对此数组执行排序。

str中的字符串可以表示正整数和负整数。这些字符串的最大长度为1024个字符。

我知道此问题的一种解决方案是将字符串转换为数字，然后将它们分开比较。还有其他解决方案吗？

Answer 1

另一种解决方案是实现自己的比较功能：

检查两个字符串的第一个字符。如果一个以数字开头，另一个以-开头，则以-开头的字符串是较小的数字。
如果两个字符串都以数字开头，则比较字符串的长度字符串。字符串越短，数字越小。如果两个字符串长度相同，执行标准字符串比较。
如果两个字符串均以-开头，则比较字符串的长度字符串。字符串越长，数字越小。如果两个字符串都相同长度，执行标准字符串比较，但取反结果。

Answer 2

这是一个最小且可能不足（不能处理前导零，空白等）的示例，可以满足您的要求。

评论解释了它在做什么。：）

#include <algorithm>
#include <iostream>
#include <string>
#include <vector>

int main() {
  std::vector<std::string> strings = {
      "-1", "-1", "-20", "-4", "3", "0", "-0", "1", "20", "20", "44020",
  };

  // Assumes everything in "strings" has no whitespace in it.
  // Assumes everything in "strings" does not have leading zeroes.
  // Assumes everything in "strings" is an ascii representaion of an integer.
  // Assumes everything in "strings" is nonempty.
  std::sort(strings.begin(), strings.end(),
            [](const std::string &a, const std::string &b) {
              const bool a_is_negative = a[0] == '-';
              const bool b_is_negative = b[0] == '-';
              if (a_is_negative != b_is_negative) {
                // If they have different signs, then whichever is negative is
                // smaller.
                return a_is_negative;
              } else if (a.length() != b.length()) {
                // If they have the same sign, then whichever has more
                // characters is larger in magnitude. When the sign is negative,
                // the longer (more digits) number is "more negative". When
                // positive, the longer (more digits) number is "more positive".
                return (a.length() < b.length()) != a_is_negative;
              } else {
                // Otherwise a lexicographic comparison of "a" and "b" will
                // determine which string is larger in magnitude. Using the same
                // logic above, we account for the "negative vs. positive"
                // comparison.
                return (a < b) != a_is_negative;
              }
            });

  for (const auto &str : strings) {
    std::cout << str << " ";
  }
  std::cout << std::endl;
}

如何在C ++中对同时包含负数和正数的字符串数组进行排序？

2 个答案: