浮点数三分 https://www.acwing.com/problem/content/4180/

整数三分 https://www.acwing.com/problem/content/106/

//三分浮点数
double l=0.0,r=1000;
while(r - l > EPS) {
    double lmid = l + (r - l) / 3;
    double rmid = r - (r - l) / 3;
    double lans = f(lmid),rans = f(rmid);
    // 求凸函数的极大值
    if(lans <= rans) l = lmid;
    else r = rmid;

    // 求凹函数的极小值
    if(lans >= rans) l = lmid;
    else r = rmid;
}
// 输出 l 或 r 都可
// cout << l << endl;
printf("%.4lf\n",f(l));

//三分整数
int l = 1,r = 40000;
while(l < r) {
    int lmid = l + (r - l) / 3;
    int rmid = r - (r - l) / 3;
    lans = f(lmid),rans = f(rmid);
        // 求凹函数的极小值
    if(lans <= rans) r = rmid - 1;
    else l = lmid + 1;
        // // 求凸函数的极大值
    if(lasn >= rans) l = lmid + 1;
    else r = rmid - 1;
}
    // 求凹函数的极小值
cout << min(lans,rans) << endl;

课件地址七年级

链接：https://pan.baidu.com/s/1d6yy1I0GtD4LKafZpPOaZg?pwd=8888 提取码：8888