leetcode Day69 剑指19-23

1470. 重新排列数组

var shuffle = function(nums, n) {
    let res=[]
    for(let i=0;i<n;i++){
        res.push(nums[i])
        res.push(nums[i+n])
    }
    return res
};

剑指 Offer 19. 正则表达式匹配

var isMatch = function(s, p) {
    const m=s.length
    const n=p.length
    const dp=new Array(m+1).fill(0).map(()=>new Array(n+1).fill(0))
    dp[0][0]=true
    for(let i=1;i<=n;i++){
        dp[0][i]=false
    }
    for(let i=2;i<=n;i+=2){
        dp[0][i]=dp[0][i-2]&&p[i-1]==="*"
    }
    for(let i=1;i<=m;i++){
        dp[i][0]=false
    }
    const match=(i,j)=>{
        if(j==='.'){
            return true
        }if(j!=='.'){
            if(i===j){
                return true
            }
        }
        return false
    }
    for(let i=1;i<=m;i++){
        for(let j=1;j<=n;j++){
            if(p[j-1]!=="*"){
                if(match(s[i-1],p[j-1])){
                    dp[i][j]=dp[i-1][j-1]
                }else{
                    dp[i][j]=false
                }
            }else{
                if(match(s[i-1],p[j-2])){
                    dp[i][j]=dp[i-1][j]|dp[i][j-2]
                }else{
                    dp[i][j]=dp[i][j-2]
                }
            }
        }
    }
    return dp[m][n]
};

946. 验证栈序列

var validateStackSequences = function(pushed, popped) {
    let stack=[]
    let j=0
    for(let i=0;i<pushed.length;i++){
        stack.push(pushed[i])
        while(stack.length!==0 && stack[stack.length-1]===popped[j]){
            stack.pop()
            j++
        }
    }
    return stack.length===0
};

剑指 Offer 21. 调整数组顺序使奇数位于偶数前面

var exchange = function(nums) {
    let l=0,r=nums.length-1
    while(l<r){
        while(l<r && nums[l]%2===1){
            l++
        }
        while(l<r && nums[r]%2===0){
            r--
        }
        if(l<r){
            let temp=nums[l]
            nums[l]=nums[r]
            nums[r]=temp
        }
    }
    return nums
};

剑指 Offer 22. 链表中倒数第k个节点

var getKthFromEnd = function(head, k) {
    let node=head
    let length=0
    while(node){
        length++
        node=node.next
    }
    let vhead=head
    for(let i=0;i<length-k;i++){
        vhead=vhead.next
    }
    return vhead
};