UVa 1626 括号序列

 1 #include<iostream> 
 2 #include<algorithm>
 3 #include<string>
 4 #include<cstring>
 5 using namespace std;
 6 
 7 char s[105];
 8 int n;
 9 int d[105][105];
10 
11 
12 bool cmp(char a, char b)
13 {
14     return a == ‘(‘&& b == ‘)‘ || (a == ‘[‘&& b == ‘]‘);
15 }
16 
17 void dp()
18 {
19 
20     for (int i = 0; i < n; i++)
21     {
22         d[i + 1][i] = 0;    //初始化，对应于下面的d[i+1][j-1]
23                             //也就是如果为()或[]，此时不需要添加括号
24         d[i][i] = 1;        //这个对应于单个‘(‘、‘)‘、‘[‘、‘]‘的情况
25     }
26 
27     //从短区间开始枚举
28     for (int i = n - 2; i >= 0; i--)
29     {
30         for (int j = i + 1; j < n; j++)
31         {
32             d[i][j] = n;
33             //如果为()or[]，则这最外面的不用管
34             if (cmp(s[i], s[j]))     d[i][j] = min(d[i][j], d[i + 1][j - 1]);
35             for (int k = i; k < j; k++)
36                 d[i][j] = min(d[i][j], d[i][k] + d[k + 1][j]);
37         }
38     }
39 }
40 
41 
42 void print(int i, int j)
43 {
44     if (i>j)    return;
45     if (i == j)
46     {
47         if (s[i] == ‘(‘ || s[i] == ‘)‘)      cout << "()";
48         else cout << "[]";
49         return;
50     }
51     int ans = d[i][j];
52     //如果和里面所要加的括号数一样，那么 i 和 j 是不需要加括号的
53     if (cmp(s[i], s[j]) && ans == d[i + 1][j - 1])
54     {
55         cout << s[i];
56         print(i + 1, j - 1);
57         cout << s[j];
58         return;
59     }
60 
61     for (int k = i; k < j; k++)
62     {
63         if (ans == d[i][k] + d[k + 1][j])
64         {
65             print(i, k);
66             print(k + 1, j);
67             return;
68         }
69     }
70 }
71 
72 int main()
73 {
74     //freopen("D:\\txt.txt", "r", stdin);
75     int T;
76     cin >> T;
77     getchar();
78     while (T--)
79     {
80         gets(s);
81         gets(s);
82         n = strlen(s);
83         dp();
84         print(0, n - 1);
85         cout << endl;
86         if (T) cout << endl;
87     }
88     return 0;
89 }