Introduction to the Young's Matrix implementation code (c + +) algorithm 6.3

Personal Summary:

The difference between 1.int **p and int a[m][n]:

1) int * * Pointer to pointer, the latter type is the array name, the type is int (*) [N], which points to the entire row.

2) (a+1) address increase m*sizeof (int), one thing to note is that a[i] is the address at the beginning of line I, &a and A are the same value. The array is of a size, and the pointer is a variable that stores the address. Deliberately to look at the declaration of the Assembly code of the array, one of the instructions is MOV%gs:0x14,%eax (array size 20 that is 0x14), and finally also seems to check whether the array overflow, overflow will call a stack function (not very understand, it should be a protection mechanism). In particular, when sizeof (array name) is called, the assembly code does not increase because the size of the array is stored in a position on the stack.

When transferring parameters, it is important to note whether the transfer should be a pointer or an array. I thought I could do this at first. int **p=a; naive! ）

#include <iostream>#include<algorithm>using namespacestd;#defineInt_max 100000classy_matrix{ Public: Y_matrix (intRowsintcols); ~Y_matrix (); voidYm_build (int*a,intN); voidPrintm ()Const; voidDecrease_key (intXintYintkey); intextract_min (); voidInsert_key (intkey) {        if(Y_matrix[r-1][c-1] !=Int_max) {cout<<"Over flow"<<Endl; return; } decrease_key (R-1C1, key); }    voidSort (int*array,intN); BOOLFind (intelem); voidClear ();Private:    Const intR, C; int**Y_matrix; voidYm_heapify (intXinty);}; Y_matrix::y_matrix (intRowsintcols): R (rows), C (cols) {Y_matrix=New int*[rows];  for(inti =0; i < rows; ++i) {Y_matrix[i]=New int[cols];  for(intj =0; J < cols; ++j) {Y_matrix[i][j]=Int_max; }    }}voidy_matrix::clear () { for(inti =0; i < R; ++i) for(intj =0; J < C; ++j) Y_matrix[i][j]=Int_max;}voidY_matrix::ym_build (int*a,intN) {    inttemp = MIN (n, r*b);  for(inti =0; I < temp; ++i)    {Insert_key (a[i]); }}voidY_matrix::ym_heapify (intXinty) {    intR = x, c =y; if(x +1< R&&y_matrix[r][c] > y_matrix[x +1][y])++x; if(Y +1< C&&y_matrix[x][y] > y_matrix[r][c +1]) {x=R; ++y; }    if(! (r = = X&&c = =y))        {Swap (Y_matrix[x][y], y_matrix[r][c]);    Ym_heapify (x, y); }}voidY_matrix::D Ecrease_key (intXintYintkey) {    if(X > R-1|| Y > C-1)        return; if(key>Y_matrix[x][y]) {cout<<"new element is bigger"<<Endl; return; }     while(1){        intR = x, c =y; Y_matrix[x][y]=key; if(X >0&& Key < Y_matrix[x-1][y]) {--x; }        if(Y >0&& Y_matrix[x][y] < y_matrix[r][c-1]) {x=R; --y; }        if(! (r = = X&&c = =y))        {Swap (Y_matrix[x][y], y_matrix[r][c]); }        Else{Y_matrix[x][y]=key;  Break; }    }}inty_matrix::extract_min () {inttemp = y_matrix[0][0]; y_matrix[0][0] =Int_max; Ym_heapify (0,0); returntemp;}voidY_matrix::sort (int*array,intN)    {Clear ();    Ym_build (array, n); intk = min (n, r*C);  for(inti =0; I < K; ++i) {Array[i]=extract_min (); }}BOOLY_matrix::find (intkey) {    intx = R-1; inty =0;  while(x >=0&& y <C) {        if(Y_matrix[x][y] >key)--x; Else if(Y_matrix[x][y] <key)++y; Else return true; }    return false;}voidY_matrix::P Rintm ()Const {     for(inti =0; i < R; ++i) {         for(intj =0; J < C; ++j) cout<< Y_matrix[i][j] <<"\ t"; cout<<Endl; } cout<<Endl;} Y_matrix::~Y_matrix () { for(inti =0; i < R; ++i)Delete[]y_matrix[i]; Delete[]y_matrix;}intMain () {inta[ +] = {4,6,8,2,1,0,7,4,2,1,9,5,1,111,2224, at,545,134,1122}; Y_matrix ym (5,5); Ym. Ym_build (A, +); Ym.    Printm (); Ym. Sort (A, +);  for(inti =0; I < +; ++i) cout<< A[i] <<" ";}

Introduction to the Young's Matrix implementation code (c + +) algorithm 6.3