Sum and Sort Items

Question

In general, I already thought it was all working, but it turned out wrong. Need to re-code

Code:

int suma(int **math, int m, int n) { int x1, x2, summa = 0; for (x1 = 0; x1 < m - 1; x1++) { for (x2 = 0; x2 < n - 1; x2++) { if ((x1 % 2 == 0) && (x2 % 2 == 0)) { summa = summa + math[x1][x2]; } } } printf("Summa: %d", summa); }

The sum of elements, both indices of which are even. But for some reason wrongly believes. I thought the idea is true, since the index looks and if it is divided into two without a trace, then we consider it. For example, [2] [4] we take the element of the matrix in the sum, but the element [1] [2] does not take. Where is the mistake? n-1 took, as C, numbering from scratch. Think so.

Code:

 int sortirovka(int **math, int m, int n) { int x1, x2, k, s = 0; printf("n"); printf("tNew Matrix:nn"); for (x1 = 0; x1 < m; x1++) { for (k = n - 1; k > 0; k--) { for (x2 = 0; x2 < k; x2++) { if (math[x1][x2] > math[x1][x2 + 1]) { s = math[x1][x2]; math[x1][x2] = math[x1][x2 + 1]; math[x1][x2 + 1] = s; } } } } for (x1 = 0; x1 < m; x1++) { for (x2 = 0; x2 < n; x2++) { printf(" %d", math[x1][x2]); } printf("n"); } }

Organize strings in a non-descending order of their largest elements. It does not work this way, the elements are sorted in rows , not the lines themselves. Therefore, you need to adjust to sort the lines themselves.

Example

1 2 7 4 3 5 2 0 9

Must issue

4 3 5 //наибольший элемент 5 1 2 7 //наибольший элемент 7 2 0 9 //наибольший элемент 9

And now gives out

1 2 7 3 4 5 0 2 9

Help correct the code.

The answer was never received. I asked the question to correct the code, and did not write that it is bad or good, I just study, so I can be understood
@ wapdimon72u, did you limit the cycle limits when calculating the amount?
Write the function swapstr (int ** a, int N, int M, int str1, str2)
Yes, it was true, it was I correct it, everything works as it should, but tell me what is notfin = 1;
About notfin is in response, a sign that the array is not yet sorted.
w is just an auxiliary variable for exchanging values, because Python a, b = b, a not provided in C / C ++.

Accepted Answer · 2012-03-03T14:37:45

Here

  for (x1 = 0; x1 < m - 1; x1++) { for (x2 = 0; x2 < n - 1; x2++) {

Why m-1 and n-1, but not m and n? And the sorting is very strange, some kind of Michurin hybrid of a bubble and (I don't know what is called) the oak itself.

Addition:

 int suma(int **math, int m, int n) { int x1, x2, summa = 0; for (x1 = 0; x1 < m; x1 += 2) for (x2 = 0; x2 < n; x2 += 2) summa = summa + math[x1][x2]; printf("Summa: %d", summa); }

Amount. Only considering the elements math [0] [0] (the first element of the first line), math [2] [2] to be even or odd is another matter.

 int sortirovka(int **math, int m, int n) { int x1, x2, k, s = 0; printf("n"); printf("tNew Matrix:nn"); for (x1 = 0; x1 < m; x1++) for (k = 0; k < n-1; k++) for (x2 = k+1; x2 < n; x2++) if (math[x1][k] > math[x1][x2]) { s = math[x1][x2]; math[x1][x2] = math[x1][k]; math[x1][k] = s; } for (x1 = 0; x1 < m; x1++) for (x2 = 0; x2 < n; x2++) { printf(" %d", math[x1][x2]); } printf("\n"); }

The sorting is the most oak (I do not remember the name, as I already said). The first element of the line is taken and compared with the rest. If more - mutually exchange. Further, with the second, third, etc. to [n-2]. The number of comparisons does not depend on the initial ordering of the array.

Check these edits - did not check.

Added:

 int suma(int **math, int m, int n) { int x1, x2, summa = 0; for (x1 = 1; x1 < m; x1 += 2) for (x2 = 1; x2 < n; x2 += 2) summa = summa + math[x1][x2]; printf("Summa: %d", summa); } int sortirovka(int **math, int m, int n) { int x1, x2, k, s = 0, *maxelems, notfin; printf("n"); // поиск максимальных элементов в строках maxelems = (int *) malloc(sizeof(int)*m); // исправлено for(x1=0; x1 < m; x1++) { maxelems[x1] = math[x1][0]; for(x2=1; x2 < n; x2++) if(maxelems[x1] < math[x1][x2]) maxelems[x1] = math[x1][x2]; } printf("tNew Matrix:nn"); notfin = 1; // признак того, что сортировка не закончена while(notfin) { notfin = 0; // сброс. Если перемещения строк не будет, то останется нулём for (x1 = 0; x1 < m-1; x1++) if(maxelems[x1] > maxelems[x1+1]) { int *w = math[x1]; // вспомогательная переменная для обмена указателей на строки int w1 = maxelems[x1]; // вспомогательная переменная для обмена максимальных значений в строках. Должны перемещаться синхронно // math[x1] <-> math[x1+1] и maxelems[x1] <-> maxelems[x1+1] math[x1] = math[x1+1]; math[x1+1] = w; maxelems[x1] = maxelems[x1+1]; maxelems[x1+1] = w1; notfin = 1; // обмен был. будет следующий просмотр массива } } for (x1 = 0; x1 < m; x1++) for (x2 = 0; x2 < n; x2++) { printf(" %d", math[x1][x2]); } printf("\n"); free(maxelems); // освобождение памяти массива максимальных значений по строкам. }

There was an error in the type in the string

  maxelems = malloc(sizeof(int*)*m);

d.b.

  maxelems = (int *) malloc(sizeof(int)*m);

I can no longer comment, the limit has been reached. notfin - a sign that the sorting is not yet complete. When sorting the bubble, the neighboring values are compared and, if necessary, are swapped. After the first pass, the array is not yet sorted. We carry out the second, etc. A sign that the array is sorted is the lack of movement of values when browsing. Somewhere like that.

The sum. The elements of the whole matrix are counted, the synumbering is from zero, therefore it is even considered to count [1] [1] [1] [3] and so on, and about sorting, this code does the same thing as mine, that is, it sorts the lines in the rows, NOT the lines themselves
As for even / odd - you just need to change the initial values of x1 = 1 and x2 = 1.
Secondly, if you have c ++ (although in this case malloc is better not to use - non-kosher, better new / delete) and there is no #include <stdlib.h> then it will be cursed at the undeclared (no prototype) function malloc (for c ++ it is better maxelems = new int[m]; and delete [] maxelems; instead of free).

Sum and Sort Items

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