题目:
一共有n道题,每道题有对应的分值grade和需要消耗的时间time,求解在规定的时间内,能得到最大的分数。
解题思路:
使用动态规划,求解最大分数。如果需要求解具体做题步骤,则需要把最大分数进行回溯,逐步找到做过的题。
这里由于题目只要求了求出最大分数,所以只编程实现了求解最大分数的目的。
代码如下:
package test;
public class DynamicProgrammingTest {
private int length;
private int[] grade;
private int[] time;
private int TimeSum;
public DynamicProgrammingTest(int length,int grade[],int time[],int TimeSum) {
// TODO Auto-generated constructor stub
this.length = length;
this.grade = grade;
this.time = time;
this.TimeSum = TimeSum;
}
public int getMaxGrade() {
//画表格
int MaxGrade[][] = new int[grade.length][TimeSum + 1];
for (int i = 0;i < grade.length;i++) {
MaxGrade[i][0] = 0;
}
for (int i = 0;i < TimeSum + 1;i++) {
//这里用i <= time[0]一直不对。。卡了很久。。尬。。
if (i < time[0]) {
MaxGrade[0][i] = 0;
}else {
MaxGrade[0][i] = grade[0];
}
}
//填表格
for (int i = 1;i < grade.length;i++) {
for (int j = 1;j < TimeSum + 1;j++) {
if (j < time[i]) {
MaxGrade[i][j] = MaxGrade[i-1][j];
}
else {
MaxGrade[i][j] = max(MaxGrade[i-1][j],MaxGrade[i-1][j-time[i]]+grade[i]);
}
}
}
for (int i = 0;i < grade.length;i++) {
for (int j = 0;j < TimeSum + 1;j++) {
System.out.print(MaxGrade[i][j]+",");
}
System.out.println();
}
return MaxGrade[grade.length - 1][TimeSum];
}
public int max(int a,int b) {
if (a>b) {
return a;
}
else return b;
}
public static void main(String[] args) {
int n = 5;
int grade[] = {1,4,3,5,4};
int time[] = {1,3,2,4,1};
int TimeSum = 6;
System.out.println(new DynamicProgrammingTest(n, grade, time, TimeSum).getMaxGrade());
}
}