Question

我有n个数组。每个数组都有m个元素。每个元素m由两个属性[数字]组成。

{
  start: x
  end: y
}

开始和结束编号，两者一起描述范围。所以每次开始都小于结束。我试图找到自由数字范围（再次使用开始和结束），它们位于所有数组中的范围元素之间。另外，结果是在一个范围内。

例如：

var boundary = {
    start: 0,
    end: 600
};

// for example i use two arrays with ranges, but in reality they are n (>= 1)
var numbersRanges1 = [
    {start: 100, end: 120},
    {start: 180, end: 200},
    {start: 400, end: 500}
];

var numbersRanges2 = [
    {start: 10, end: 80},
    {start: 150, end: 220},
    {start: 480, end: 500}
];

// result should look like
var expected = [
    {start: 0, end: 10},
    {start: 80, end: 100},
    {start: 120, end: 150},
    {start: 220, end: 400},
    {start: 500, end: 600}
];

这是我目前的工作解决方案（JS Bin）

var boundary = {
    start: 0,
    end: 600
};

// for example i use two arrays with ranges, but in reality they are n (>= 1)
var numbersRanges1 = [
    {start: 100, end: 120},
    {start: 180, end: 200},
    {start: 400, end: 500}
];

var numbersRanges2 = [
    {start: 10, end: 80},
    {start: 150, end: 220},
    {start: 480, end: 500}
];

// result should look like
var expected = [
    {start: 0, end: 10},
    {start: 80, end: 100},
    {start: 120, end: 150},
    {start: 220, end: 400},
    {start: 500, end: 600}
];

// merge arrays
var mergedRanges = numbersRanges1.concat(numbersRanges2);


// sort by start
function sortByStart(a, b){
    return a.start - b.start;
}

mergedRanges = mergedRanges.sort(sortByStart);

// group overlapping ranges
for(var i = 1; i < mergedRanges.length; i++){
    var range1 = mergedRanges[i-1];
    var range2 = mergedRanges[i];

    if((range1.start <= range2.end) && (range1.end >= range2.start)){
        range2.start = Math.min(range1.start, range2.start);
        range2.end = Math.max(range1.end, range2.end);
        mergedRanges.splice(i-1, 1);
    }
}

// go throw merged ranges and save ranges between in addition array
var freeRanges = [];

if(mergedRanges[0].start > boundary.start){
    freeRanges.push({
        start: boundary.start,
        end: mergedRanges[0].start
    });
}

for(var i = 1, mergedLen = mergedRanges.length; i <  mergedLen; i++){
    freeRanges.push({
        start: mergedRanges[i-1].end,
        end: mergedRanges[i].start
    });
}

if(mergedRanges[mergedLen-1].end < boundary.end){
    freeRanges.push({
        start: mergedRanges[mergedLen-1].end,
        end: boundary.end
    });
}

console.log(freeRanges);
console.log(expected);

该脚本在node.js服务器上运行。因为我们做了很多这样的并发计算，所以我试图为此找到一种资源有效且高性能的算法。有没有更好的方法来实现这一目标？他们的代码中是否存在任何陷阱，导致性能问题？

Answer 1

这是一个简化版本。

// for example i use two arrays with ranges, but in reality they are n (>= 1)
var numbersRanges1 = [
    {start: 100, end: 120},
    {start: 180, end: 200},
    {start: 400, end: 500}
];

var numbersRanges2 = [
    {start: 10, end: 80},
    {start: 150, end: 220},
    {start: 480, end: 500}
];

var boundary = {
    start: 0,
    end: 600
};

// merge arrays
var mergedRanges = numbersRanges1.concat(numbersRanges2);

// sort by start
function sortByStart(a, b){
    return a.start - b.start;
}

mergedRanges = mergedRanges.sort(sortByStart);

// go throw merged ranges and save ranges between in addition array
var freeRanges = [];

var start=0;
mergedRanges.forEach(function(one) {
  if(one.start<start) return;
  freeRanges.push({start:start,end:one.start});
  start=one.end;
});

if(start<boundary.end) {
  freeRanges.push({start:start,end:boundary.end});
}

console.log(JSON.stringify(freeRanges,null,2));

如何在其他重叠数字范围之间找到空闲数字范围

1 个答案: