leetcode

4 两个排序数组的中位数

class Solution {
public:
    double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2) {
        int n=nums1.size(),m=nums2.size();
        if(n>m){
            swap(n,m);
            swap(nums1,nums2);
        }
        int l=0,r=n,mid1=0,mid2=0;
        while(l<=r){
            mid1=(l+r)>>1;
            mid2=((n+m+1)>>1)-mid1;
            if((mid1==0||mid2==m||nums1[mid1-1]<=nums2[mid2])&&(mid1==n||mid2==0||nums2[mid2-1]<=nums1[mid1])) break;
            else if((mid1>0&&mid2<m&&nums1[mid1-1]>nums2[mid2])){
                r=mid1-1;
            }else if(mid1<n&&mid2>0&&nums2[mid2-1]>nums1[mid1]){
                l=mid1+1;
            }
        }
        cout<<"l r: "<<l<<' '<<r<<endl;
        cout<<"mid1 mid2: "<<mid1<<' '<<mid2<<endl;
        int maxL=0,minR=0;
        if(mid1==0) maxL=nums2[mid2-1];
        else if(mid2==0) maxL=nums1[mid1-1];
        else maxL=max(nums1[mid1-1],nums2[mid2-1]);
        if(mid1==n) minR=nums2[mid2];
        else if(mid2==m) minR=nums1[mid1];
        else minR=min(nums1[mid1],nums2[mid2]);
        cout<<maxL<<' '<<minR<<endl;
        if((n+m)%2==0) return (maxL+minR)/2.0;
        else return maxL;
    }
};

5 最长回文字串

class Solution {
public:
    string longestPalindrome(string s) {
        string str="$+";
        for(int i=0;i<s.length();i++){
            str+=s[i];
            str+="+";
        }
        str+="%";
        s=str;
        cout<<s<<endl;
        int maxl=0,n=s.length(),id=0,mx=0,d[2009];
        string ans="";
        memset(d,0,sizeof(d));
        for(int i=1;i<n;i++){
            if(i<mx){
                d[i]=min(mx-i,d[2*id-i]);
            }else{
                d[i]=1;
            }
            while(s[i-d[i]]==s[i+d[i]]) d[i]++;
            if(mx<i+d[i]){
                mx=i+d[i];
                id=i;
            }
            if(d[i]-1>maxl){
                maxl=d[i]-1;
                ans="";
                for(int j=i-d[i]+1;j<=i+d[i]-1;j++){
                    if(s[j]!='+') ans+=s[j];
                }    
            }
        }
        return ans;
    }
};

10 正则表达式匹配

class Solution {
public:
    bool isMatch(string s, string p) {
        int n=s.length(),m=p.length();
        if(n==0&&m==0) return 1;
        if(n==1&&m==1) return s[0]==p[0]||p[0]=='.';
        if(p[1]!='*'){
            if(n==0) return 0;
            if(p[0]==s[0]||p[0]=='.') return isMatch(s.substr(1),p.substr(1));
            else return 0;
        }
        while(!s.empty()&&(s[0]==p[0]||p[0]=='.')){
            if(isMatch(s,p.substr(2))) return 1;
            s=s.substr(1);
        }
        return p.length()>=2?isMatch(s,p.substr(2)):0;
    }
};