题解 | #自动售货系统#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Comparator;

public class Main {
    public static void main(String[] args) {
        int[][] a1 = new int[][] { { 1, 2, 0 }, { 2, 3, 0 }, { 3, 4, 0 },
            { 4, 5, 0 }, { 5, 8, 0 }, { 6, 6, 0 }
        };
        int[][] a2 = new int[][] { { 1, 0 }, { 2, 0 }, { 5, 0 }, { 10, 0 } };
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        StringBuffer bu = new StringBuffer();
        String rTip = "S001:Initialization is successful\n";
        String[] pTips = { "S002:Pay success,balance=",
                           "E002:Denomination error\n",
                           "E003:Change is not enough, pay fail\n",
                           "E005:All the goods sold out\n"
                         };
        String[] bTips = { "S003:Buy success,balance=",
                           "E006:Goods does not exist\n", "E007:The goods sold out\n",
                           "E008:Lack of balance\n"
                         };
        String cTip = "E009:Work failure\n";
        String qTip = "E010:Parameter error\n";
        String a = null;
        try {
            a = in.readLine();
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        int i = 0, j, l = a.length(), pMon, index = 0, indexM = 0, b = 0;
        int[] cCnt = null;
        boolean boolen2;
        char[] chrAy = new char[l];
        char[] chrAySub;
        a.getChars(0, l, chrAy, 0);
        int[][] comm = init(chrAy, l);
        for (i = 0; i < comm.length; i++) {
            chrAySub = new char[comm[i][1]];
            System.arraycopy(chrAy, comm[i][0], chrAySub, 0, comm[i][1]);
            switch (chrAySub[0]) {
                case 'r'://初始化
                    rFunc(chrAySub, a1, a2);
                    bu.append(rTip);// 初始化成功信息
                    break;
                case 'p':
                    pMon = getPMoney(chrAySub);
                    index = pFunc(a1, a2, pMon);
                    b = index == 0 ? b + pMon : b;// 投币余额
                    bu.append(index == 0 ? pTips[index] + b + "\n" :
                              pTips[index]);//投币余额放入输入信息
                    break;
                case 'b':
                    boolen2 = bIfBuy(chrAySub);
                    indexM = bGetM(chrAySub, a1);
                    if (!boolen2)
                        index = 1;
                    else if (a1[indexM][2] == 0)
                        index = 2;
                    else if (b < a1[indexM][1]) {
                        index = 3;
                    } else {
                        index = 0;
                        a1[indexM][2]--;// 该商品数量-1
                        b -= a1[indexM][1];
                    }
                    bu.append(index == 0 ? bTips[index] + b + "\n" : bTips[index]);
                    break;
                case 'c':
                    if (b == 0)
                        bu.append(cTip);
                    else {
                        cCnt = cFunc(a2, b);
                        b = 0;
                        for (j = 0; j < cCnt.length; j++) {
                            bu.append(a2[j][0] + " yuan coin number=" + cCnt[j])
                            .append("\n");
                        }
                    }
                    break;
                case 'q':
                    if (chrAySub.length != 3)
                        bu.append(qTip);
                    else if (chrAySub[2] == '0') {
                        Arrays.sort(a1, new Comparator<int[]>() {//按数量排序
                            public int compare(int[] i1, int[] i2) {
                                return i2[2] - i1[2];
                            }
                        });
                        for (j = 0; j < a1.length; j++) {
                            index = a1[j][0];
                            bu.append("A" + index + " " + a1[j][1] + " " + a1[j][2]
                                      + "\n");
                        }
                    } else if (chrAySub[2] == '1') {
                        for (j = 0; j < a2.length; j++) {
                            bu.append(a2[j][0] + " yuan coin number=" + a2[j][1]
                                      + "\n");
                        }
                    }
                    break;
            }
        }
        System.out.print(bu);
    }

    // 将输入字符串命令分割为命令个数数组，第一列存放一条命令的开始初始索引，第二列存放命令长度
    static int[][] init(char[] chrAy, int l) {
        int i = 0, j = 0, index = 0, commCnt = 0;
        for (; i < l; i++) {
            if (chrAy[i] == ';')
                commCnt++;
        }
        int[][] indeAndLen = new int[commCnt][2];
        for (i = 0; i < l; i++) {
            if (chrAy[i] == ';') {
                indeAndLen[j][0] = index;
                indeAndLen[j][1] = i - index;//该条命令的长度
                index = i + 1;//分号后一位为下一条命令开始
                j++;
            }
        }
        return indeAndLen;
    }

    // 执行r初始化商品和钱币的数量
    static void rFunc(char[] chrArr, int[][] arr1, int[][] arr2) {
        int i = 2, j = 0, l = chrArr.length, n = 0;
        boolean transfer = false;// 是否是钱币的数量
        for (; i < l; i++) {
            if (chrArr[i] == '-') {
                if (transfer)
                    arr2[j++][1] = n;
                else
                    arr1[j++][2] = n;
                n = 0;
            } else if (chrArr[i] == ' ') {
                arr1[j++][2] = n;
                n = 0;
                j = 0;
                transfer = true;
            } else {
                n *= 10;
                n += chrArr[i] - '0';
                if (i == l - 1)
                    arr2[j][1] = n;
            }
        }
    }

    // 获得投入的钱币的值
    public static int getPMoney(char[] chrArr) {
        int i = 1, l = chrArr.length, mon = 0;
        for (; i < l; i++) {
            if (chrArr[i] == ' ')
                continue;
            mon *= 10;
            mon += chrArr[i] - '0';
        }
        return mon;
    }

    // 投入钱币的成功与否判断
    static int pFunc(int[][] a1, int[][] a2, int mon) {
        int i = 1, l = 0, index = 0, sum1And2 = 0, stuffCnt = 0;
        boolean monHas = false;
        for (i = 0; i < a1.length; i++) {
            stuffCnt += a1[i][2];// 剩余商品数量
        }
        l = a2.length;
        i = 0;
        for (; i < l; i++) {
            if (mon == a2[i][0]) {
                monHas = true;
                break;// 记录钱币在钱币数组a2中的索引
            }
        }
        sum1And2 = a2[0][0] * a2[0][1] + a2[1][0] *
                   a2[1][1];// 剩余1元和2元的总钱数
        if (!monHas)
            index = 1;// 将投入的该钱币退出
        else if ((mon == a2[2][0] || mon == a2[3][0]) && sum1And2 < mon) {
            index = 2;// 将投入的该钱币退出
        } else if (stuffCnt == 0) {
            index = 3;// 将投入的该钱币退出
        } else {
            a2[i][1]++;// 该面值的钱币数量+1
        }
        return index;
    }

    // 判断该商品是否能够购买
    static boolean bIfBuy(char[] chrArr) {
        int l = chrArr.length;
        return chrArr[l - 2] == 'A'
               && (chrArr[l - 1] - '0' | '6' - chrArr[l - 1]) > 0;
    }

    // 获得商品的索引
    static int bGetM(char[] chrArr, int[][] a1) {
        int i = 0, l = chrArr.length;
        int ind = chrArr[l - 1] - '0';
        for (; i < a1.length; i++) {
            if (ind == a1[i][0])
                break;
        }
        return i;
    }

    static int[] cFunc(int[][] a2,
                       int mon) {// 数组初始化只能在方法外部，要么返回该数组
        int l = a2.length, i = l - 1, j, monE;
        int[] cCnt = new int[l];
        for (; i >= 0; i--) {//从10元到1元，遍历钱币数组
            monE = a2[i][0];//该钱币面值
            j = mon / monE;//大面值能找零，则先找大面值
            if (a2[i][1] == 0 || j == 0) {//余额不足或者该面值数量0，跳过
                cCnt[i] = 0;
                continue;
            }
            if (j > a2[i][1]) {//找零的数量超过该面值总数量
                cCnt[i] = a2[i][1];//只找出该面值总数
                a2[i][1] = 0;//该面值数量变为0
                mon -= cCnt[i] * monE;
            } else {
                cCnt[i] = j;
                a2[i][1] -= j;
                mon -= j * monE;
            }
        }
        return cCnt;
    }
}