第一题01背包public static int ks(int[] day, int[] value, int day1) {
            int size = day.length;
            if (size == 0) {
                return 0;
            }

            int[][] dp = new int[size][day1 + 1];
            for (int i = 0; i <= day1; i++) {
                dp[0][i] = day[0] <= i ? value[0] : 0;
            }
            for (int i = 1; i < size; i++) {
                for (int j = 0; j <= day1; j++) {
                    dp[i][j] = dp[i - 1][j];
                    if (day[i] <= j) {
                        dp[i][j] = Math.max(dp[i][j], value[i] + dp[i - 1][j - day[i]]);
                    }
                }
            }
            return dp[size - 1][day1];
        }

        public static void main(String[] args) {
            Scanner scan=new Scanner(System.in);
            int num=scan.nextInt();
            for(int i=0;i<num;i++) {
                int num1=scan.nextInt();
                int day=scan.nextInt();
                int[] value=new int [num1];
                int []day1=new int[num1];
                for(int j=0;j<num1;j++) {
                     value[j]=scan.nextInt();
                     day1[j]=scan.nextInt();
                }
                System.out.println(ks(day1,value,day));
            }
        }
第三题我是用的递归求解约束判断  因为会重复的 所有我先存了一下判断，代码比较low 不 喜勿喷
public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scan=new Scanner(System.in);
        int num1=scan.nextInt();
        int num2=scan.nextInt();
        int [] price=new int[num2];
        for(int i=0;i<num2;i++) {
            price[i]=scan.nextInt();
        }
        int like=scan.nextInt();
        int []likeall=new int[like];
        for(int i=0;i<like;i++) {
            likeall[i]=scan.nextInt()-1;
        }
        int []count=new int[num2];
        int []countall=new int[1];
        countall[0]=0;
        int [] []flagg=new int[1000][num2];
        int []nums={0};
        dfs(num1,price,count,likeall,countall,flagg,nums);
        System.out.print(countall[0]);
    }
     public static void dfs(int num,int []price,int []count,int []like,int []countall,int[][]flagg,int[] nums) {
         for(int i=0;i<price.length;i++) {
             num=num-price[i];
             count[i]++;
             if(num<0){
                 count[i]--;
                 return;
             }
             if(num==0) {
                 int flag=1;
                 for(int j=1;j<like.length;j++) {
                       if(count[like[j]]-count[like[j-1]]>=0) {
                           flag=0;
                       }
                 }
                 if(flag==1) {
                     for(int q=0;q<flagg.length;q++) {
                         int flags=0;
                         for(int y=0;y<count.length;y++) {
                             if(flagg[q][y]!=count[y]) {
                                 flags=1;
                                 break;
                             }
                         }
                         if(flags==0) {
                             count[i]--;
                             return;
                         }
                     }
                     for(int x = 0;x<count.length;x++) {
                         flagg[nums[0]][x]=count[x];
                     }
                     nums[0]++;
                     countall[0]++;
                 }
                 count[i]--;
                 return ;
             }
             if(num>0) {
                 dfs(num,price,count,like,countall,flagg,nums);
                 count[i]--;
                 num=num+price[i];
             }
         }
         return;
     }