foo.cc: In function 'int main()':
foo.cc:35:13: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
             if(queue[tail].s==k)//判断是否到达终点
             ^~
foo.cc:37:14: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
              tail++;
              ^~~~
foo.cc:62:9: warning: unused variable 'i' [-Wunused-variable]
     int i;
         ^

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