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Brackets sequence
Description:
Let us define a regular brackets sequence in the following way:
1.Empty sequence is a regular sequence.
2.If S is a regular sequence, then (S) and [S] are both regular sequences.
3.If A and B are regular sequences, then AB is a regular sequence.
For example, all of the following sequences of characters are regular brackets sequences:
(), [], (()), ([]), ()[], ()[()]
And all of the following character sequences are not:
(, [, ), )(, ([)], ([(]
Some sequence of characters ‘(‘, ‘)‘, ‘[‘, and ‘]‘ is given. You are to find the shortest possible regular brackets sequence, that contains the given character sequence as a subsequence. Here, a string a1a2...an is called a subsequence of the string b1b2...bm, if there exist such indices 1 ≤ i1 < i2 < ... < in ≤ m, that aj=bij for all 1 ≤ j ≤ n.
Input
The input begins with a single positive integer on a line by itself indicating the number of the cases following, each of them as described below. This line is followed by a blank line, and there is also a blank line between two consecutive inputs.
The input file contains at most 100 brackets (characters ‘(‘, ‘)‘, ‘[‘ and ‘]‘) that are situated on a single line without any other characters among them.
Output
For each test case, the output must follow the description below. The outputs of two consecutive cases will be separated by a blank line.
Write to the output file a single line that contains some regular brackets sequence that has the minimal possible length and contains the given sequence as a subsequence.
Sample Input
1
([(]
Sample Output
()[()]
# include <cstdio> # include <cstring> # include <algorithm> # include <iostream> using namespace std; int d[105][105],len; //数组 d 的含义,从第 i 个字符到第 j 字符需要匹配多少括号; char s[105]; bool match(char a , char b) //判断是否括号匹配; { if(a=='('&&b==')'|| a=='['&&b==']') return true; else return false; } void dp( ) { int i,j,k; for(i=0;i<len;i++) //数据重置; { d[i+1][i]=0; d[i][i]=1; } for(i=len-2;i>=0;i--) //从倒数第二个字符串开始; { for(j=i+1;j<len;j++) { d[i][j] = len; //如果最外层的括号是匹配的,那么把下标往里移动; if( match (s[i],s[j]) ) d[i][j] = min (d[i][j],d[i+1][j-1]); //继续寻找最优解; for(k=i;k<j;k++) d[i][j] = min ( d[i][j],d[i][k] + d[k+1][j] ); } } } void print(int i,int j) //其实就是倒推的过程; { if( i>j ) return ; if( i==j ) { if( s[i]=='('||s[i]==')' ) printf("()"); else printf("[]"); return ; } int ans = d [i] [j]; if( match(s[i],s[j]) && ans== d[i+1][j-1] ) //判断最外层的两个括号是不是匹配的,再看最优值是不是dp [i-1] [j+1]; { printf("%c",s[i]); print(i+1,j-1); printf("%c",s[j]); return ; } for( int k =i; k<j ;k++) { if( ans == d[i][k]+d[k+1][j] ) { print( i, k); print( k+1, j); return ; } } } void readline(char *s) { fgets(s,105,stdin); } int main() { int n; readline(s); sscanf(s, "%d", &n); readline(s); while(n--) { readline(s); len=strlen(s)-1; memset(d,-1,sizeof(d)); dp(); print(0,len-1); cout<<"\n"; if(n) cout<<"\n"; readline(s); } return 0; }
Brackets sequence