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POCompute Absolute values of N integer combinations Combinations
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copied!<p>For a N number (a..N) I am finding set of all combinations in the following way:</p> <pre><code>void create_print_combinations(int *t, int x, int n) { if(x == 0) { char p [2 * r + 2]; memset (p, 0, 2 * r +2); for (int j=c;j>0;j--) if(j == c) sprintf(p, "%d", t[j]); else sprintf(p, "%s,%d", p,t[j]); print_combi(p); } else { for (int i= n; i < r; i++) { t[x] = a[i]; create_print_combinations(t, x-1, i+1); } } } </code></pre> <p>So a call to function like:</p> <pre><code>int main() { unsigned long int start=0, end=0; printf ("\nEnter the a positive integer N:"); scanf("%d", &r); start=time(NULL); a = new int[r]; for (int i = 0;i<r;i++) a[i]=i+1; for(int j=1;j<=r;j++) { a1 = new int[j]; c=j; create_print_combinations(a1, c, 0); delete[] a1; } end=time(NULL); printf("Total time taken = %llu\n" , end - start); return 0; } </code></pre> <p>Gives me combinations like for N=4:</p> <p>Enter the a positive integer N:4</p> <pre><code>Combo : [1] Combo : [2] Combo : [3] Combo : [4] Combo : [1,2] Combo : [1,3] Combo : [1,4] Combo : [2,3] Combo : [2,4] Combo : [3,4] Combo : [1,2,3] Combo : [1,2,4] Combo : [1,3,4] Combo : [2,3,4] Combo : [1,2,3,4] </code></pre> <p>Now my tasks is to fond the absolute values of all combinations like:</p> <p>For Combo [1,2,3,4] it should be:</p> <pre><code>1+2+3+4 = abs(1+2+3+4) 1+2+3-4 = abs(1+2+3-4) 1+2-3-4 = .. 1-2-3+4 = ... </code></pre> <p>Ans so on</p> <p>I am trying the below logic:</p> <pre><code>while(pos > 0) { for(int a=0; a < i; a++) { if(a==0) sprintf(p,"%d", t[a]); else if(a == pos) sprintf(p,"%s%c%d",p, minus, t[a]); else sprintf(p,"%s%c%d",p, plus, t[a]); } print(p); memset (p , 0, 2 * r +2); pos --; } </code></pre> <p>But I beleiev I am doing something wrong as all sets are not getting printed. I am unable to frame the logic though I feel I am near to completion. Below is my whole program:</p> <pre><code>#include <stdio.h> #include <string.h> #include <stdlib.h> #include <ctype.h> #include <time.h> int *a; int *a1; int r; int c; unsigned long int no =1; int stoi(char *var) { int n1 = 0; int n2 = 0; int n3 = 0; char sign=0; while(*var) { if(isspace(*var)) { var++; continue; } while(*var >= '0' && *var <= '9') { n1=(n1*10) + (*var - '0'); var++; continue; } if(sign == '+') { n2=n2+n1; n1=0; } else if(sign == '-') { n2=n2 - n1; n1=0; } if(*var == '+' || *var == '-') { if(sign == 0) { n2=n1; n1=0; } sign = *var; } var++; } if(sign == 0) return abs(n1); return abs(n2); } void print(char* var) { printf("[Combo %llu.] %s = %d\n" , no++, var, stoi(var)); } void print_combi(char * a) { int t[c]; char *x = NULL; char *y = a; int i=0; while((x=strchr(y, ',')) != NULL) { *x = '\0'; t[i++]=atoi(y); y=x+1; } t[i++]=atoi(y); int count =0; int loop = 0; char p [2 * r + 2]; memset (p , 0, 2 * r +2); char plus = '+'; char minus = '-'; for(int k=0;k<2;k++) { if(k==1) { plus = '-'; minus = '+'; } if(i>1) { for(int a=0; a < i; a++) { if(a==0) sprintf(p,"%d", t[a]); else sprintf(p,"%s%c%d",p, plus, t[a]); } } else if(i==1) { sprintf(p,"%d", t[i-1]); print(p); break; } print(p); memset (p , 0, 2 * r +2); if(i==2) continue; if(i==3 && k ==1) break; int pos = i-1; while(pos > 0) { for(int a=0; a < i; a++) { if(a==0) sprintf(p,"%d", t[a]); else if(a == pos) sprintf(p,"%s%c%d",p, minus, t[a]); else sprintf(p,"%s%c%d",p, plus, t[a]); } print(p); memset (p , 0, 2 * r +2); pos --; } } } void create_print_combinations(int *t, int x, int n) { if(x == 0) { char p [2 * r + 2]; memset (p, 0, 2 * r +2); for (int j=c;j>0;j--) if(j == c) sprintf(p, "%d", t[j]); else sprintf(p, "%s,%d", p,t[j]); print_combi(p); } else for (int i= n; i < r; i++) { t[x] = a[i]; create_print_combinations(t, x-1, i+1); } } int main() { unsigned long int start=0, end=0; printf ("\nEnter the a positive integer N:"); scanf("%d", &r); start=time(NULL); a = new int[r]; for (int i = 0;i<r;i++) a[i]=i+1; for(int j=1;j<=r;j++) { a1 = new int[j]; c=j; create_print_combinations(a1, c, 0); delete[] a1; } end=time(NULL); printf("Total time taken = %llu\n" , end - start); return 0; } </code></pre> <p>As per the program logic I am computing the combinations as strings and the generating the absolute values of the expression.</p>

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