算法5：售票员找零

 

*售票员

*新的《复仇者》电影刚刚上映！电影院售票处有很多人排起了长队。他们每人有一张100、50或25美元的钞票（每人只有一张纸币）。一张“复仇者”的票要25美元。

*瓦西娅目前是一名职员。他想把票卖给这一行的每一个人。

*如果瓦西娅一开始没有钱，而且严格按照人们排队的顺序售票，他能不能给每个人一张票，并找零钱？

*如果瓦西娅可以把票卖给每个人，然后用他手头的钞票找零，返回YES。否则返回NO

 

    public static String Tickets(int[] peopleInLine, int lineNo) {

        final String RESULT_YES = "YES";
        final String RESULT_NO = "NO";
        String res = null;

        final int twentyFive = 25;
        final int fifty = 50;
        final int oneHundred = 100;

        int cnt_twentyFive = 0;
        int cnt_fifty = 0;
        int cnt_oneHundred = 0;

        //peopleInLine = new int[]{25, 25, 50};
        for (int i = 0; i < peopleInLine.length; i++) {
            if (peopleInLine[i] == twentyFive) {
                cnt_twentyFive++;
            } else if (peopleInLine[i] == fifty) {
                cnt_fifty++;
            } else if (peopleInLine[i] == oneHundred) {
                cnt_oneHundred++;
            }
        }
        if (cnt_oneHundred == 0 && cnt_fifty == 0 && cnt_twentyFive != 0) {
            res = RESULT_YES;
        } else if (cnt_oneHundred == 0 && cnt_fifty != 0 && cnt_twentyFive != 0) {
            if (cnt_fifty <= cnt_twentyFive) {
                res = RESULT_YES;
            } else {
                res = RESULT_NO;
            }
        } else if (cnt_oneHundred != 0 && cnt_fifty == 0 && cnt_twentyFive != 0) {
            if (cnt_oneHundred * 3 <= cnt_twentyFive) {
                res = RESULT_YES;
            } else {
                res = RESULT_NO;
            }
        } else if (cnt_oneHundred != 0 && cnt_fifty != 0 && cnt_twentyFive != 0) {
            if (cnt_oneHundred <= cnt_fifty && cnt_fifty * 2 <= cnt_twentyFive) {
                res = RESULT_YES;
            } else if (cnt_oneHundred > cnt_fifty && (cnt_oneHundred - cnt_fifty) * 3 <= cnt_twentyFive - cnt_fifty * 2) {
                res = RESULT_YES;
            } else {
                res = RESULT_NO;
            }
        } else {
            res = RESULT_NO;
        }

        System.out.println(" cnt_oneHundred = " + cnt_oneHundred + ",\n cnt_fifty = " + cnt_fifty + ",\n cnt_twentyFive = " + cnt_twentyFive + ",\n RESULT = " + res + "\n   This Tickets" + lineNo + " is over! \n");
        return res;
    }



    public static void main(String[] args) {
        // test
        Tickets(new int[]{25, 25, 25, 25}, 1); // lineNo.1: only have 25: YES
        Tickets(new int[]{25, 25, 50, 50, 25, 50}, 2); // lineNo.2: only have 25 50: cnt_fifty <= cnt_twentyFive YES
        Tickets(new int[]{100, 100, 25, 25, 25, 25, 25, 25}, 3); // lineNo.3: only have 25 100: cnt_oneHundred * 3 <= cnt_twentyFive YES
        Tickets(new int[]{100, 50, 50, 25, 25, 25, 25, 25}, 4); // lineNo.4: have 25 50 100: cnt_oneHundred  <= cnt_fifty && cnt_fifty * 2 <= cnt_twentyFive YES
        Tickets(new int[]{100, 100, 100, 50, 50, 25, 25, 25, 25, 25, 25, 25}, 5); // lineNo.5: have 25 50 100: cnt_oneHundred > cnt_fifty && (cnt_oneHundred - cnt_fifty) * 3 <= cnt_twentyFive - cnt_fifty * 2 YES
        Tickets(new int[]{100, 50, 50, 25, 25}, 6); // lineNo.6: NO
    }

　　结果：

cnt_oneHundred = 0,
 cnt_fifty = 0,
 cnt_twentyFive = 4,
 RESULT = YES
   This Tickets1 is over! 

 cnt_oneHundred = 0,
 cnt_fifty = 3,
 cnt_twentyFive = 3,
 RESULT = YES
   This Tickets2 is over! 

 cnt_oneHundred = 2,
 cnt_fifty = 0,
 cnt_twentyFive = 6,
 RESULT = YES
   This Tickets3 is over! 

 cnt_oneHundred = 1,
 cnt_fifty = 2,
 cnt_twentyFive = 5,
 RESULT = YES
   This Tickets4 is over! 

 cnt_oneHundred = 3,
 cnt_fifty = 2,
 cnt_twentyFive = 7,
 RESULT = YES
   This Tickets5 is over! 

 cnt_oneHundred = 1,
 cnt_fifty = 2,
 cnt_twentyFive = 2,
 RESULT = NO
   This Tickets6 is over!