POJ 1141 Brackets Sequence

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 using namespace std;
 5 const int maxn = 105;
 6 const int inf = 0x3f3f3f3f;
 7 char str[maxn];
 8 int dp[maxn][maxn];
 9 
10 bool match(char a, char b){
11     return (a==‘(‘&&b==‘)‘) || (a==‘[‘&&b==‘]‘);
12 }
13 
14 int dfs(int l, int r){
15     if (l > r)
16         return dp[l][r] = 0;
17     if (l == r)
18         return dp[l][r] = 1;
19     if (dp[l][r] != inf)
20         return dp[l][r];
21     int ans = dp[l][r];
22     if (match(str[l], str[r]))
23         ans = min(ans, dfs(l+1, r-1));
24     for (int i=l; i<r; ++i)
25         ans = min(ans, dfs(l, i)+dfs(i+1, r));
26     return dp[l][r] = ans;
27 }
28 
29 void print(int l, int r){
30     if (l > r)
31         return ;
32     if (l == r){
33         if (str[l]==‘(‘ || str[r]==‘)‘)
34             printf("()");
35         else
36             printf("[]");
37         return ;
38     }
39     int ans = dp[l][r];
40     if (match(str[l], str[r]) && ans==dp[l+1][r-1]){
41         putchar(str[l]);
42         print(l+1, r-1);
43         putchar(str[r]);
44         return ;
45     }
46     for (int i=l; i<r; ++i)
47         if (ans == dp[l][i]+dp[i+1][r]){
48             print(l, i);
49             print(i+1, r);
50             return ;
51         }
52 }
53 
54 int main(){
55     while (fgets(str, maxn, stdin)){
56         int n = strlen(str);
57         str[n-1] = ‘\0‘;
58         --n;
59         memset(dp, inf, sizeof(dp));
60         dfs(0, n-1);
61         print(0, n-1);
62         putchar(‘\n‘);
63     }
64     return 0;
65 }