leetcode简单(数组,字符串,链表)：[168, 171, 190, 205, 228, 448, 461, 876, 836, 844]

目录

• 168. Excel表列名称
• 171. Excel 表列序号
• 190. 颠倒二进制位
• 205. 同构字符串
• 228. 汇总区间
• 448. 找到所有数组中消失的数字
• 461. 汉明距离
• 876. 链表的中间结点
• 836. 矩形重叠
• 844. 比较含退格的字符串

168. Excel表列名称

var convertToTitle = function(columnNumber) {
    let str = ''
    let n = columnNumber
    while (n) {
        let y = n % 26 // 从后往前取余
        n = n / 26 | 0 // 除以26并且向下取整
        y || n-- // 余数为0 ，n--
        str = String.fromCharCode(64 + (y || 26)) + str
    }
    return str
};

171. Excel 表列序号

var titleToNumber = function(columnTitle) {
    let result = 0;
    let s = columnTitle;
    for (let i = 0, len = s.length; i < len; i++) {
        result += (s[i].charCodeAt() - 64) * 26 ** (len - i - 1);
    }
    return result;
};

190. 颠倒二进制位

var reverseBits = function(n) {
    return parseInt((n).toString(2).padStart(32, '0').split('').reverse().join(''), 2)
};

205. 同构字符串

var isIsomorphic = function(s, t) {
    let sMap = {}
    let tMap = {}
    for (let i = 0; i < s.length; i++) {
        if (sMap[s[i]] !== tMap[t[i]]) return false
        sMap[s[i]] = i
        tMap[t[i]] = i
    }
    return true
};

228. 汇总区间

var summaryRanges = function(nums) {
    if (nums.length == 0) return []

    let left = 0,
        right = 0
    let res = []
    for (let i = 0; i < nums.length; i++) {
        if (nums[i] + 1 === nums[i + 1]) {
            right++
        } else {
            res.push(left === right ? `${nums[i]}` : `${nums[left]} -> ${nums[right]}`)
            left = i + 1
            right = i + 1
        }
    }
    return res
};

448. 找到所有数组中消失的数字

var findDisappearedNumbers = function(nums) {
    var res = []
    for (let i = 1; i <= nums.length; i++) {
        if (nums.indexOf(i) === -1) {
            res.push(i)
        }
    }
    return res
};

461. 汉明距离

var hammingDistance = function(x, y) {
    var binX = x.toString(2)
    var binY = y.toString(2)
    var len = binX.length > binY.length ? binX.length : binY.length
    binX = binX.padStart(len, '0')
    binY = binY.padStart(len, '0')
    var disCount = 0
    for (let i = 0; i < len; i++) {
        if (binX[i] !== binY[i]) {
            disCount++
        }

    }
    return disCount
};

876. 链表的中间结点

var middleNode = function(head) {
    let slow = head
    let fast = head
    while (fast !== null && fast.next !== null) {
        slow = slow.next
        fast = fast.next.next
    }
    return slow
};

836. 矩形重叠

var isRectangleOverlap = function(rec1, rec2) {
    if (rec1[0] >= rec2[2] || rec1[2] <= rec2[0] || rec1[1] >= rec2[3] || rec1[3] <= rec2[1]) {
        return false
    }
    return true

};

844. 比较含退格的字符串

var backspaceCompare = function(s, t) {
    let i = s.length - 1
    let j = t.length - 1
    let backSpaceS = 0
    let backSpaceT = 0

    while (i >= 0 || j >= 0) {
        while (i >= 0) {
            if (s[i] == '#') {
                backSpaceS++
                i--
            } else if (backSpaceS > 0) {
                backSpaceS--
                i--
            } else {
                break
            }
        }
        while (j >= 0) {
            if (t[j] == '#') {
                backSpaceT++
                j--
            } else if (backSpaceT > 0) {
                backSpaceT--
                j--
            } else {
                break
            }
        }
        if (s[i] !== t[j]) {
            return false
        }
        i--
        j--
    }
    return true
};