贪心

贪心

1个维度【生活常识】

135. 分发糖果

class Solution {
    public boolean lemonadeChange(int[] bills) {
		int[] arr = new int[2];
		for (int bill : bills) {
			if (bill == 5){
				arr[0]++;
			}else if (bill == 10){
				if (arr[0] > 0){
					arr[0]--;
					arr[1]++;
				}else {
					return false;
				}
			}else {	//	20【fw：不会进行收集】
				if (arr[1] > 0){	//	有 10 块
					arr[1]--;
					if (arr[0] > 0){
						arr[0]--;
					}else {
						return false;
					}
				}else {	//	没有 10 块钱
					if (arr[0] >= 3){
						arr[0] -= 3;
					}else {
						return false;
					}
				}
			}
		}
		return true;
	}
}

2个维度【要分别考虑：挑选合适的】

406. 根据身高重建队列

先身高，同时 count 小的在前 ====> 保证当前坐标的前方都是比自己大于等于的 ===> 然后再去一点点微调整

class Solution {
    public int[][] reconstructQueue(int[][] people) {
		List<man> list = new ArrayList<>();
		for (int[] person : people) {
			list.add(new man(person[0], person[1]));
		}
		Collections.sort(list, (o1, o2) -> {
			if (o1.height != o2.height) {
				return o2.height - o1.height;	//	身高大的在前
			}
			return o1.count - o2.count;	//	count 小的在前
		});
		List<man> men = new ArrayList<>();
		int[][] arr = new int[people.length][2];
		for (int i = 0; i < arr.length; i++) {
			man man = list.get(i);
			if (man.count == i){
				men.add(man);
			}else {
				men.add(man.count, man);
			}
		}
		for (int i = 0; i < arr.length; i++) {
			man man = men.get(i);
			arr[i][0] = man.height;
			arr[i][1] = man.count;
		}
		return arr;
	}
}

class man{
	int height;
	int count;

	public man(int height, int count) {
		this.height = height;
		this.count = count;
	}
}

OD 高效的任务规划【按照运行时间降序，（配置时间（累加） + 运行时间）取 max】

import java.util.Scanner;
import java.util.*;


// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int count = Integer.parseInt(in.nextLine());
        for (int i = 0; i < count; i++) {
            int temp = Integer.parseInt(in.nextLine());
            List<machine> list = new ArrayList<>();
            for (int j = 0; j < temp; j++) {
                String[] split = in.nextLine().split(" ");
                int time1 = Integer.parseInt(split[0]);
                int time2 = Integer.parseInt(split[1]);
                list.add(new machine(time1, time2));
            }
            Collections.sort(list, (o1, o2) -> o2.time2 - o1.time2);  //  1. 按照运行时间降序
            int res = 0;
            int config_time = 0;
            for (int j = 0; j < list.size(); j++) {
                machine machine = list.get(j);
                config_time += machine.time1;  //  2. 配置时间累加
                res = Math.max(res, config_time + machine.time2);  //  3. 取 max
            }
            System.out.println(res);
        }
    }
}

class machine{
    int time1;
    int time2;

    public machine(int time1, int time2) {
        this.time1 = time1;
        this.time2 = time2;
    }
}