从number中找出3个连续数字的最大和

Question

我有一个任务是写一个C程序，找出数字中3个连续数字的最大和。这是我写的，但我遇到了麻烦:程序似乎运行得很好，但它并没有输入正确的答案，而是键入了一些奇怪的数字。例如，如果输入为"560315"，则响应为"155“。但是，如果我键入"560415“，答案仍然是"155”，如果我键入"561315“，则响应将更改为"156”。这是编码的问题吗？代码如下：

#include <stdio.h>
int isempt(int a) {
if ((a==' ')||(a=='\n')||(a=='\t')) {
    return 1;
}
else return 0;
}

main() {
int a, b, c, d, e, i, maxsum;
a = 0;
b = 0;
c = 0;
d = 0;
maxsum = 0;
i = 0;
int counter = 0; //the variables "numsearch" and "inside" indicate whether program is in the number or outside it
int numsearch = 1; 
int inside = 0;
while ((i = getchar())!=EOF) {
    if (numsearch==1) {
        if (isempt(i)==0) {
            numsearch = 0;
            inside = 1;
            a = i;
            counter++;
        }
        }
    else if ((isempt(i)==0)&&(inside==1)) {
            if (counter == 1) {
                b = i;
                counter++;
            }
            else if (counter == 2) {
                c = i;
                counter++;
            }
            else if (counter == 3) {
                d = i;
                maxsum = a+b+c;
                if ((b+c+d) > maxsum) {
                    maxsum =( b+c+d);
                }
                a =b;
                b = c;
                c = d;
                counter++;
            }
            else if (counter == 4) {
                d = i;
                if ((b+c+d)>maxsum) {
                    maxsum = b+c+d;
                }
                a=b;
                b=c;
                c=d;
            }

            }
        else if ((counter>=3)&&(isempt(i)==1)) {
                printf("\n%d\n", maxsum );
                counter = 0;
                numsearch = 1;
                inside = 0;
                a = 0;
                b = 0;
                c = 0;
                d = 0;
            }
            else {
                counter = 0;
                numsearch = 1;
                inside = 0;
                a = 0;
                b = 0;
                c = 0;
                d = 0;

            }
        }
    }

Answer 1

要解决这个问题，您可以在每次使用变量i的值将其赋给算法的变量时从i中减去48：a，b，c，d，在这种情况下，示例560316的答案将是11，我相信它是3个连续数字的最大和，这是可行的，因为48是数字0的ascii代码,49是数字1的ascii代码，因此您的代码应该是这样的：

        #include <stdio.h>
        int isempt(int a) {
        if ((a==' ')||(a=='\n')||(a=='\t')) {
            return 1;
        }
        else return 0;
        }

        void main() {
        int a, b, c, d, e, i, maxsum;
        a = 0;
        b = 0;
        c = 0;
        d = 0;
        maxsum = 0;
        i = 0;
        int counter = 0; //the variables "numsearch" and "inside" indicate whether program is in the number or outside it
        int numsearch = 1; 
        int inside = 0;
        while ((i = getchar())!=EOF) {
            if (numsearch==1) {
                if (isempt(i)==0) {
                    numsearch = 0;
                    inside = 1;
                    a = i - '0';
                    counter++;
                }
                }
            else if ((isempt(i)==0)&&(inside==1)) {
                    if (counter == 1) {
                        b = i - '0' ;
                        counter++;
                    }
                    else if (counter == 2) {
                        c = i - '0';
                        counter++;
                    }
                    else if (counter == 3) {
                        d = i - '0';
                        maxsum = a+b+c;
                        if ((b+c+d) > maxsum) {
                            maxsum =( b+c+d);
                        }
                        a =b;
                        b = c;
                        c = d;
                        counter++;
                    }
                    else if (counter == 4) {
                        d = i - '0' ;
                        if ((b+c+d)>maxsum) {
                            maxsum = b+c+d;
                        }
                        a=b;
                        b=c;
                        c=d;
                    }

                    }
                else if ((counter>=3)&&(isempt(i)==1)) {
                        printf("\n%d\n", maxsum );
                        counter = 0;
                        numsearch = 1;
                        inside = 0;
                        a = 0;
                        b = 0;
                        c = 0;
                        d = 0;
                    }
                    else {
                        counter = 0;
                        numsearch = 1;
                        inside = 0;
                        a = 0;
                        b = 0;
                        c = 0;
                        d = 0;

                    }
                }
            }

Answer 2

你有这么多嵌套的条件句，我想你可能把自己搞糊涂了。我相信创建一个整数数组会更容易，并且在数组的每个索引处初始化为零。然后将索引指示的数字加1(第一个数字到第0个索引，第二个数字到第一个索引，等等)到该索引和前面的两个索引(如果它们存在，您必须进行边界检查)。然后只需找到并打印数组中最大的数字。

Answer 3

@T-D很好地涵盖了主要问题:使用a = i - '0'而不是a = i。(在4个地方)

@Jonah Nelson确实指出嵌套有点过了。下面是一个简化的版本。

操作码在处理既不是空格也不是数字的文本时确实有问题。

#include <stdio.h>
#include <ctype.h>

int main() {
  int ch;
  int index = 0;
  char history[2];
  int maxsum = -1;
  int sum = 0;  // running sum
  while ((ch = getchar()) != EOF) {
    if (isdigit(ch)) {
      ch -= '0';  // Convert text code to `int` value.
      sum += ch;
      if (index >= 2) {
        if (sum > maxsum) {
          maxsum = sum;
        }
        sum -= history[0];
        history[0] = history[1];
        history[1] = ch;
      }
      else {
        history[index++] = ch;
      }
    }
    else {
      if (!isspace(ch)) {
        printf("Unexpected text '%c'\n", ch);
      }
      index = 0;
      sum = 0;
    }
  }
  printf("Maximum sum: %d\n", maxsum);
  return maxsum < 0;
}