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4659:Liveness Analysis

题目描述
A program syntax is defined as below:
PROGRAM ::= STATEMENTS end '\n'
STATEMENTS ::= STATEMENT STATEMENTS | epsilon
STATEMENT ::= a [variable] '\n' | u [variable] '\n' | IF-CLAUSE
IF-CLAUSE ::= if '\n' STATEMENTS end '\n' | if '\n' STATEMENTS else '\n' STATEMENTS end '\n'

In which '\n' means the new line character, epsilon means an empty string, [variable] means a variable, which is represented by a number between 1 and n (inclusive). Same numbers denote the same variable.
The program runs as follows:
If the statement is "a [variable]", it assigns the variable a new value;
If the statement if "u [variable]", it uses value of the variable to do something interesting;
If there is an IF-CLAUSE, it is possible that condition of this clause is satisfied or not satisfied.

We only need to do liveness analysis on this program. This is why we do not explicitly write assigned values, what we do with the variables and condition of IF-CLAUSEs.
In this task, there are three kinds of liveness for each of the variables.
1. Live. In one or more paths of this program, value of the variable at the beginning of the program is used.
2. Dead. In all paths of this program, the variable is assigned a new value before any use of this variable.
3. Half-dead. In all paths of this program, value of the variable at the beginning of the program is not used, but in one or more paths, the variable is never assigned a new value.
输入解释
First line, number of test cases, T.
Following are T test cases. For each test case, the first line is n, number of variables in the program. The following lines is the program.

Number of lines in the input <= 500000
输出解释
T lines. Each line contains n numbers. If the variable is live, output 1; if the variable is dead, output -1; if the variable is half-dead, output 0.
输入样例
10
1
end
1
a 1
end
1
u 1
end
1
a 1
u 1
end
1
u 1
a 1
end
1
if
a 1
else
a 1
end
end
1
if
a 1
else
u 1
end
end
1
if
a 1
end
end
1
if
u 1
end
end
2
a 1
u 2
end
输出样例
0
-1
1
-1
1
-1
1
0
1
-1 1
来自杭电HDUOJ的附加信息
Recommend zhuyuanchen520

该题目是Virtual Judge题目,来自 杭电HDUOJ

源链接: HDU-4659

最后修改于 2020-10-25T23:15:34+00:00 由爬虫自动更新

共提交 0

通过率 --%
时间上限 内存上限
2000/1000MS(Java/Others) 131072/65536K(Java/Others)