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| 1 | +/* |
| 2 | +You're now a baseball game point recorder. |
| 3 | +
|
| 4 | +Given a list of strings, each string can be one of the 4 following types: |
| 5 | +
|
| 6 | +Integer (one round's score): Directly represents the number of points you get in this round. |
| 7 | +"+" (one round's score): Represents that the points you get in this round are the sum of the last two valid round's points. |
| 8 | +"D" (one round's score): Represents that the points you get in this round are the doubled data of the last valid round's points. |
| 9 | +"C" (an operation, which isn't a round's score): Represents the last valid round's points you get were invalid and should be removed. |
| 10 | +Each round's operation is permanent and could have an impact on the round before and the round after. |
| 11 | +
|
| 12 | +You need to return the sum of the points you could get in all the rounds. |
| 13 | +
|
| 14 | +Example 1: |
| 15 | +Input: ["5","2","C","D","+"] |
| 16 | +Output: 30 |
| 17 | +Explanation: |
| 18 | +Round 1: You could get 5 points. The sum is: 5. |
| 19 | +Round 2: You could get 2 points. The sum is: 7. |
| 20 | +Operation 1: The round 2's data was invalid. The sum is: 5. |
| 21 | +Round 3: You could get 10 points (the round 2's data has been removed). The sum is: 15. |
| 22 | +Round 4: You could get 5 + 10 = 15 points. The sum is: 30. |
| 23 | +Example 2: |
| 24 | +Input: ["5","-2","4","C","D","9","+","+"] |
| 25 | +Output: 27 |
| 26 | +Explanation: |
| 27 | +Round 1: You could get 5 points. The sum is: 5. |
| 28 | +Round 2: You could get -2 points. The sum is: 3. |
| 29 | +Round 3: You could get 4 points. The sum is: 7. |
| 30 | +Operation 1: The round 3's data is invalid. The sum is: 3. |
| 31 | +Round 4: You could get -4 points (the round 3's data has been removed). The sum is: -1. |
| 32 | +Round 5: You could get 9 points. The sum is: 8. |
| 33 | +Round 6: You could get -4 + 9 = 5 points. The sum is 13. |
| 34 | +Round 7: You could get 9 + 5 = 14 points. The sum is 27. |
| 35 | +Note: |
| 36 | +The size of the input list will be between 1 and 1000. |
| 37 | +Every integer represented in the list will be between -30000 and 30000. |
| 38 | +
|
| 39 | +来源:力扣(LeetCode) |
| 40 | +链接:https://leetcode-cn.com/problems/baseball-game |
| 41 | +著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。 |
| 42 | +*/ |
| 43 | + |
| 44 | +/* O(N) in time and O(N) in space */ |
| 45 | + |
| 46 | +#include <string> |
| 47 | +#include <vector> |
| 48 | +#include <stack> |
| 49 | +using namespace std; |
| 50 | + |
| 51 | +class Solution { |
| 52 | +public: |
| 53 | + int calPoints(vector<string>& ops) { |
| 54 | + stack<int> s; |
| 55 | + int res = 0; |
| 56 | + |
| 57 | + for(int i=0; i<(int)ops.size(); ++i){ |
| 58 | + if(ops[i][0]=='+'){ |
| 59 | + int prev1 = s.top(); s.pop(); |
| 60 | + int prev2 = s.top(); s.pop(); |
| 61 | + s.push(prev2); |
| 62 | + s.push(prev1); |
| 63 | + s.push(prev1+prev2); |
| 64 | + } |
| 65 | + else if(ops[i][0]=='D'){ |
| 66 | + s.push(2*s.top()); |
| 67 | + } |
| 68 | + else if(ops[i][0]=='C'){ |
| 69 | + s.pop(); |
| 70 | + } |
| 71 | + else{ |
| 72 | + int temp = 0; |
| 73 | + bool is_pos = true; |
| 74 | + for(int j=0; j<(int)ops[i].size(); ++j){ |
| 75 | + if(ops[i][j]=='-') is_pos = false; |
| 76 | + else temp = temp*10 + ops[i][j] - '0'; |
| 77 | + } |
| 78 | + if(is_pos) s.push(temp); |
| 79 | + else s.push(-temp); |
| 80 | + } |
| 81 | + } |
| 82 | + |
| 83 | + while(!s.empty()){ |
| 84 | + res += s.top(); s.pop(); |
| 85 | + } |
| 86 | + |
| 87 | + return res; |
| 88 | + } |
| 89 | +}; |
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