做差值

class Solution {
public:
    int month[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
    int daysBetweenDates(string date1, string date2) {
        return abs(get(date1)-get(date2));
    }
    int get(string date)
    {
        int res=0,year,mon,day;
        sscanf(date.c_str(),"%d-%d-%d",&year,&mon,&day);

        for(int i=1971;i<year;i++) res+=365+isleap(i);
        for(int i=1;i<mon;i++)
        {
            if(i==2) res+=28+isleap(year);
            else res+=month[i];
        }
        cout<<res+day<<endl;
        return res+day;
    }
    bool isleap(int x)
    {
        return (x%400==0)||x%4==0&&x%100;
    }
};

暴力加

class Solution {
public:
    int month[2][13]={{0,31,28,31,30,31,30,31,31,30,31,30,31},{0,31,29,31,30,31,30,31,31,30,31,30,31}};
    int daysBetweenDates(string date1, string date2) {
        int ans=0,n1,n2,y1,y2,r1,r2;
        if(date1>date2) swap(date1,date2);
        sscanf(date1.c_str(),"%d-%d-%d",&n1,&y1,&r1);
        sscanf(date2.c_str(),"%d-%d-%d",&n2,&y2,&r2);

        while(n1<n2||y1<y2||r1<r2)
        {
            r1++;
            int maxr=month[is(n1)][y1];

            if(r1>maxr)
            {
                r1=1;
                y1++;
            }
            if(y1>12)
            {
                y1=1;
                n1++;
            }
            ans++;
        }
        return ans;
    }
    bool is(int x)
    {
        return (x%400==0)||(x%4==0&&x%100);
    }
};