js中判断数字是否在多个区间内

function isNumberInRanges(number, ranges) {
  if (!Array.isArray(ranges)) {
    throw new Error("Ranges must be an array of arrays.");
  }

  for (const range of ranges) {
    if (!Array.isArray(range) || range.length !== 2) {
      throw new Error("Each range must be an array with two elements.");
    }

    const [min, max] = range;

    if (typeof min !== 'number' || typeof max !== 'number') {
      throw new Error("Range boundaries must be numbers.");
    }

    if (number >= min && number <= max) {
      return true; // 数字在当前区间内
    }
  }

  return false; // 数字不在任何区间内
}

// 示例用法
const ranges = [[1, 5], [10, 20], [30, 40]];
const number1 = 3;
const number2 = 25;

console.log(`${number1} 在区间 ${JSON.stringify(ranges)} 内吗? ${isNumberInRanges(number1, ranges)}`); // true
console.log(`${number2} 在区间 ${JSON.stringify(ranges)} 内吗? ${isNumberInRanges(number2, ranges)}`); // false

// 错误处理示例
try {
  console.log(isNumberInRanges(7, [[1, 5], [10, "a"]]));
} catch (e) {
  console.error(e.message); // Range boundaries must be numbers.
}

function mergeOverlappingRanges(ranges) {
  if (!Array.isArray(ranges) || ranges.length === 0) {
    return [];
  }

  // 浅拷贝并排序，避免修改原数组
  const sortedRanges = [...ranges].sort((a, b) => a[0] - b[0]);
  const mergedRanges = [sortedRanges[0]];

  for (let i = 1; i < sortedRanges.length; i++) {
    const currentRange = sortedRanges[i];
    const lastMergedRange = mergedRanges[mergedRanges.length - 1];

    if (currentRange[0] <= lastMergedRange[1]) {
      // 区间重叠，合并
      lastMergedRange[1] = Math.max(lastMergedRange[1], currentRange[1]);
    } else {
      // 区间不重叠，添加到结果数组
      mergedRanges.push(currentRange);
    }
  }

  return mergedRanges;
}

// 示例
const overlappingRanges = [[1, 3], [2, 6], [8, 10], [15, 18]];
const merged = mergeOverlappingRanges(overlappingRanges);
console.log(`合并后的区间：${JSON.stringify(merged)}`); // [[1,6],[8,10],[15,18]]

function isNumberInRangesWithInfinity(number, ranges) {
  for (const range of ranges) {
    const [min, max] = range;

    if (min === Number.NEGATIVE_INFINITY && max === Number.POSITIVE_INFINITY) {
      return true; // 数字在整个实数范围内
    } else if (min === Number.NEGATIVE_INFINITY) {
      if (number <= max) {
        return true;
      }
    } else if (max === Number.POSITIVE_INFINITY) {
      if (number >= min) {
        return true;
      }
    } else if (number >= min && number <= max) {
      return true;
    }
  }

  return false;
}

// 示例
const rangesWithInfinity = [[Number.NEGATIVE_INFINITY, 5], [10, Number.POSITIVE_INFINITY]];
console.log(isNumberInRangesWithInfinity(0, rangesWithInfinity)); // true
console.log(isNumberInRangesWithInfinity(7, rangesWithInfinity)); // false
console.log(isNumberInRangesWithInfinity(15, rangesWithInfinity)); // true