"Algorithmic Competition Primer Classic" "chapter three" after-school exercises (Part II)

I haven't written a blog since the Blue Bridge Cup. Today, the third chapter of the previous part of the problem of the answer to fill.

3-4 adding integers

This topic has the hint, said chooses the appropriate input way, can simplify the question. I didn't think of Cin at first, and the result was a string, and I remembered Cin, thanks to someone reminding me. Shame on you.

#include <iostream>using namespace Std;int main () {    int a A, B;    char op;    while (cin>>a>>op>>b) {        Switch (OP) {case            ' + ':                cout<<a+b<<endl; break;            Case '-':                cout<<a-b<<endl; break;            Case ' * ':                cout<<a*b<<endl; break;        }    }    return 0;}

3-5 rotate the character matrix counterclockwise by 90 degrees

#include <iostream> #define MAXN 10using namespace Std;int main () {    char m[maxn][maxn];    int i,j,n;    while (Cin>>n) {for        (i = 0, i < n; i++) {for            (j = 0;j<n;j++) {                cin>>m[i][j];            }        }        for (i = n-1;i>=0;i--) {for            (j = 0;j<n;j++) {                cout<<m[j][i];            }            cout<<endl;        }    }    return 0;}

3-6 binary conversion (converts decimal to other binary)

This problem I will expand the topic into a hdu2031 conversion, the following I also in the way of hdu this problem (but it seems to be no different)

#include <iostream> #include <string.h> #define MAXN 10using namespace Std;int main () {int n,b;int p,cnt; Char NUM[MAXN];    while (cin>>n>>b) {        memset (num,0,sizeof (num));        CNT = 0;        if (n<0) {            cout<< "-";            n =-n;        }        if (n<2)            cout<<n<<endl;        else{            while (n>0) {                p = n%b;                n/= B;                if (p>9)                    num[cnt++] = p + ' A '-ten;                else                    num[cnt++] = p + ' 0 ';            }            NUM[CNT] = ' + ';        }        for (int i = strlen (num) -1;i>=0;i--)            cout<<num[i];        cout<<endl;    }    return 0;}

3-7 binary conversion (converting other binary to decimal)

This topic originally wanted to expand it into a very large number of arbitrary conversions into decimal numbers, but did not think of a more concise and powerful method, so I can only question the topic.

#include <iostream> #include <string.h> #include <cmath> #define MAXN  + 10;using namespace std ; int change (int n,int b) {    int ans = 0;    int p;    for (int i = 0; n>0;i++,n/=10) {        p = (n%10) * POW (b,i);        ans + = p;    }    return ans;} int main () {int n,b;    while (cin>>n>>b) {        cout<<change (n,b) <<endl;    }    return 0;}

3-8 Phone Keypad

This one has seen a decisive table, violence resolved.

#include <stdio.h> #include <string.h> #define MAXN 10typedef struct{    char A;    Char str[10];} Ch;int Main () {    char word[maxn];    CH p[26]={{' A ', ' A1 '}, {' B ', ' b2b1 '}, {' C ', ' c3c1 '}, {' d ', ' D1 '}, {' E ', ' e2e1 '},{' f ', ' f3f1 '},{' g ', ' G1 '}    ,    {' H ', ' H2h1 "},{' I '," I3i1 "},{' J '," J1 "}, {' K '," k2k1 "},{' l '," L3L1 "}, {' m '," M1 "    }, {' n '," n2n1 "},{' O '," o3o1 "},{' P '," P1 "}, {' Q ', ' q2q1 '},    {' R ', ' R3r1 '},{' s ', ' s4s1 '},{' t ', ' T1 '}, {' U ', ' u2u1 '},{' V ', ' v3v1 '}, {'    w ', ' W1 '}, {' X ', ' x2x1 '}, {' Y ', ' y3y1 '},{' z ', ' Z4z1 '}};    while (1) {scanf ("%s", word);        for (int i = 0; i < strlen (word); i++) {                for (int j = 0; j<26;j++) {                    if (word[i]==p[j].a) {                        printf ("%s", p[ J].STR);}}}        printf ("\ n");    }    return 0;}

In this case, we will be the beginning of the classic algorithm competition is an over-the-ground.
If there is a better solution or error, please give more advice.

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"Algorithmic Competition Primer Classic" "chapter three" after-school exercises (Part II)