leetcode860. Lemonade change

One : The analects of Confucius

The little intolerance here refers to that, on the one hand, we are frustrated and can't control ourselves and lose our temper , On the other hand, we are too indecisive , For the fault of oneself or others , Do not have the heart to punish .

Two : subject

3、 ... and : Upper code

class Solution {
    
public:
    bool lemonadeChange(vector<int>& bills) {
    
        /**  Ideas :1. As long as it is 5 Just count the change  2. When you meet 10 perhaps 20 We have to judge whether our change is enough to find , If there is enough change , Then subtract from the change   Change to get back , At the same time, remember to add the money we just earned  */  

        int change = 0;
        int flag1 = 0;// Special record 5 The number of   Because when we get back the change, we should pay special attention to the necessary contents 5
        int flag2 = 0;// Special record 10 The number of 

        for(auto nums: bills) {
    
            
            if(nums == 5) {
    
                change+=nums;
                flag1++;
            }
            
            if(nums == 10) {
    
                if(change>=5 && flag1 != 0) {
    
                    change = change-5+10;
                    flag1--;
                    flag2++;
                }else {
    
                    return false;
                }
            }
            
            if(nums == 20) {
    
                if(change >= 15 && flag1 != 0 && flag2 != 0) {
    // The rest of the money should include 10 and 5
                    change = change-15+20;
                    flag1--;
                    flag2--;
                }else if(change >= 15 && flag1 >= 3) {
    // The rest of the money 5 The number of yuan is greater than 3  Namely 10 The number of yuan is 0
                    change = change-15+20;
                    flag1 = flag1-3;
                }
                else{
    
                    return false;
                }
            }
        }
        return true;
    }
};