水题,区间dp即可,转移是显然(?)的。
#include<bits/stdc++.h> using i64 = long long; int main() { std::cin.tie(nullptr)->sync_with_stdio(false); std::string s; std::cin >> s; int n = s.size(); std::vector dp(n, std::vector<int>(n, n)); for (int i = 0; i < n; i++) { dp[i][i] = 1; } std::map<char, int> mp; mp['('] = -1; mp[')'] = 1; mp['['] = -2; mp[']'] = 2; for (int i = 1; i < n; i++) { dp[i][i - 1] = 0; } for (int l = 2; l <= n; l++) { for (int i = 0; i + l - 1 < n; i++) { dp[i][i + l - 1] = std::min(dp[i][i + l - 1], dp[i + 1][i + l - 2] + (mp[s[i]] < 0 && mp[s[i]] + mp[s[i + l - 1]] == 0 ? 0 : 2)); for (int j = i; j < i + l - 1; j++) { dp[i][i + l - 1] = std::min(dp[i][i + l - 1], dp[i][j] + dp[j + 1][i + l - 1]); } } } std::cout << dp[0][n - 1]; return 0; }