foo.cc: In function 'int main()':
foo.cc:32:34: warning: format '%lf' expects argument of type 'double', but argument 2 has type 'int' [-Wformat=]
         printf("%.2lf\n", balance);
                                  ^
foo.cc:12:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &budget[i]);  // 读取输入数据
         ~~~~~^~~~~~~~~~~~~~~~~~

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