Gym - 100507H H. Pair: normal and paranormal 栈

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H - Pair: normal and paranormal

Gym - 100507H

Source

Gym - 100507H

My Solution

题意：给一个字符串，要求把大写字母和小写字母一一配对，要求不交叉。

用栈来模拟，不要写挂了就没问题，^_^
复杂度 O(n)

#include <iostream>#include <cstdio>#include <string>#include <stack>using namespace std;typedef long long LL;typedef pair<char, int> pci;const int maxn = 5e3 + 8;string s;int Ind[2*maxn], ans[maxn];stack<pci> sta;int main(){    #ifdef LOCAL    freopen("h.txt", "r", stdin);    //freopen("h.out", "w", stdout);    int T = 4;    while(T--){    #endif // LOCAL    ios::sync_with_stdio(false); cin.tie(0);    int n, ptr = 0, a = 0, A = 0;    cin >> n >> s;    for(int i = 0; i < 2*n; i++){if(islower(s[i])) Ind[i] = ++ a; else Ind[i] = ++ A; }    for(int i = 0; i < 2*n; i++){        if(!sta.empty() && isupper(sta.top().first) && tolower(sta.top().first) == s[i]){            ans[Ind[sta.top().second]] = Ind[i];            sta.pop();        }        else if(!sta.empty() && isupper(s[i]) && sta.top().first == tolower(s[i])){            ans[Ind[i]] = Ind[sta.top().second];            sta.pop();        }        else sta.push(pci(s[i], i));    }    if(sta.empty()){        cout << ans[1];        for(int i = 2; i <= n; i++){            cout << " " << ans[i];        }    }    else cout << "Impossible";    cout << endl;    #ifdef LOCAL    while(!sta.empty()) sta.pop();    cout << endl;    }    #endif // LOCAL    return 0;}

Thank you!

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