Shulou(Shulou.com)06/03 Report--

[topic description]

For a given source string and a target string, you should output the first index (from 0) of target string in source string.

If target does not exist in source, just return-1.

For a given source string and a target string, you should find the first position in the source string where the target string appears (starting at 0). If it does not exist, return-1.

[topic link]

Http://www.lintcode.com/en/problem/strstr/

[topic Analysis]

Double for loops can be used to solve the string lookup problem, and the KMP algorithm is more efficient.

Source code analysis

1. Boundary check: source and target may be empty strings.

two。 Flag overflow under boundary check: pay attention to the loop judgment condition of variable I, if it is simple I < source.length (), it may overflow in the following source.charAt (I + j).

3. Code style: (1) operator = = both sides should be added spaces; (2) variable names not from such as s1``s2, be meaningful, such as target`source; (3) even if there is only one sentence in the if statement also want to increase parentheses, that is {return-1;}; (4) Java code curly braces generally on the right side of the same line, C++ code curly braces usually start another line; (5) int I, j; statement before a line of spaces, is a good code style.

4. Do not declare iQuery j in the for condition, it is easy to cause compilation errors when it is reused outside the loop.

[answer link]

Http://www.jiuzhang.com/solutions/strstr/

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