顺次数-1291

[sl1673495]

我们定义「顺次数」为：每一位上的数字都比前一位上的数字大 1 的整数。

请你返回由  [low, high]  范围内所有顺次数组成的 有序 列表（从小到大排序）。

示例 1：

输出：low = 100, high = 300
输出：[123,234]
示例 2：

输出：low = 1000, high = 13000
输出：[1234,2345,3456,4567,5678,6789,12345]

提示：

10 <= low <= high <= 10^9

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/sequential-digits
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

思路

先通过 low和high之间的长度对比，得到总共有几种数字长度。

然后循环这些数字长度 len 作为目标， 1 作为最小起点， 10 - len 作为最大的起点，不断尝试构造出长度为 len 的顺位数字即可。

/**
 * @param {number} low
 * @param {number} high
 * @return {number[]}
 */
let sequentialDigits = function (low, high) {
  let lowLen = low.toString().length
  let highLen = high.toString().length
  let lens = []
  for (let i = lowLen; i <= highLen; i++) {
    lens.push(i)
  }

  let res = []
  for (let i = 0; i < lens.length; i++) {
    let len = lens[i]
    for (let start = 1; start <= 10 - len; start++) {
      let num = start

      for (let n = start + 1; n < start + len; n++) {
        num = 10 * num + n
      }
      if (num <= high && num >= low) {
        res.push(num)
      }
    }
  }

  return res
}

[zhangfei18]

请问递归和回溯体现在了哪里呢

[Gjb7598189]

function f(low, high) {
let l1 = low.toString().length, l2 = high.toString().length, res = [];

const lenArr = [];
for (let i = l1; i <= l2; i ++) { lenArr.push(i) };
console.log(lenArr)
for (let i = 0; i < lenArr.length; i ++) {
    const len = lenArr[i], min = 1; max = 10 - len;
    for (let j = min; j <= max; j ++) {
        var str = '', start = j;
        for (let k = 1; k <= len; k ++) {
              str += start;
                start++;
                
        }
        const num = Number(str);
        if (num >= low && num <= high) res.push(num)
    }
}

return res;

}

[Chocolate1999]

/**
 * @param {number} low
 * @param {number} high
 * @return {number[]}
 */
var sequentialDigits = function(low, high) {
    let res = []
    let lowLen = low.toString().length
    let highLen = high.toString().length
    for(let i=lowLen;i<=highLen;i++){
        for(let j=1;j<=10-i;j++){
            let str = ''
            let num = j
            str += num
            let k = i-1
            while(k--){
                num++
                str += num
            }
            let ans = parseInt(str)
            if(ans>=low && ans<=high){
                res.push(ans)
            }
        }
    }
    return res    
};

[daomingQian]

var sequentialDigits = function(low, high) {
let arr = [
12, 23, 34, 45, 56, 67, 78, 89,
123, 234, 345, 456, 567, 678, 789,
1234, 2345, 3456,4567, 5678, 6789,
12345, 23456, 34567, 45678, 56789,
123456, 234567, 345678, 456789,
1234567, 2345678, 3456789,
12345678, 23456789,
123456789
]
let res = [];
for(let num of arr){
if(num>=low && num<=high){
res.push(num);
}
}

return res;

};

[55utah]

function sequentialDigits(low: number, high: number): number[] {
    /**  对123456789字符串滑动窗口处理  */
    const sam = '123456789'
    const result = []
    const max = high.toString().length
    for (let i = low.toString().length; i <= max; i++) {
        for (let k = 0; k <= 9 - i; k++) {
            const v = Number(sam.slice(k, k + i))
            if (v >= low && v <= high) result.push(v)
            else if (v > high) break
        }
    }
    return result
}

[SuAgnes]

  var sequentialDigits = function (low, high) {
        let init = '123456789',
            len = low.toString().length,
            initI = low.toString().slice(0, 1);
            i = init.substr(initI - 1, len) >= low ? initI - 1 : initI;
            num = 0;
            res = [];
        while (num < high && len < 9) {
            if (9 - i < len) {
                len += 1;
                i = 0;
            }
            num = init.substr(i, len);
            if (num <= high) {
                res.push(num);
            }
            i++;
        }
        return res;
    };

[pandaxue]

 var lowLen = low.toString().length
 var highLen = high.toString().length    
var str = "123456789"
    var seq = [];
    while(lowLen<= highLen){
        var idx = 0
        while(lowLen + idx <= str.length) {
            var num = parseInt(str.substring(idx, idx+ lowLen))
            if(num>=low && num <= high){
                console.log(num)
                seq.push(num)
            }
            idx++
        }
        lowLen++
    }
    return seq