算法竞赛入门经典习题2-6 排列(permutation)
暴力解法:
1 #include <stdio.h> 2 #include <stdlib.h> 3 4 int compare(const void *a, const void *b); 5 6 int main(int argc, char **argv){ 7 int i,j,k; 8 int arr[9]; 9 for(i=100;i<333;i++){ 10 for(j=200;j<666;j++){ 11 for(k=300;k<1000;k++){ 12 arr[0] = i/100; 13 arr[1] = (i/10)%10; 14 arr[2] = i%10; 15 arr[3] = j/100; 16 arr[4] = (j/10)%10; 17 arr[5] = j%10; 18 arr[6] = k/100; 19 arr[7] = (k/10)%10; 20 arr[8] = k%10; 21 qsort(arr, 9, sizeof(int),compare); 22 int m; 23 for( m = 0; m<9; m++){ 24 if(arr[m] != m+1){ 25 break; 26 } 27 } 28 if(m == 9){ 29 if(k%i==0 && j%i == 0 && k/i == 3 && j/i == 2){ 30 printf("%d %d %d\n",i,j,k); 31 } 32 } 33 } 34 } 35 } 36 return 0; 37 } 38 int compare(const void *a, const void *b){ 39 return *(int*)a - *(int*)b; 40 }
vs.
1 #include <stdio.h> 2 #include <stdlib.h> 3 4 int compare(const void *a, const void *b); 5 6 int main(int argc, char **argv){ 7 int arr[9]; 8 int abc, def, ghi; 9 for(abc = 100; abc <334; abc++){ 10 def = 2 * abc; 11 ghi = 3 * abc; 12 arr[0] = abc/100; 13 arr[1] = (abc/10)%10; 14 arr[2] = abc%10; 15 arr[3] = def/100; 16 arr[4] = (def/10)%10; 17 arr[5] = def%10; 18 arr[6] = ghi/100; 19 arr[7] = (ghi/10)%10; 20 arr[8] = ghi%10; 21 qsort(arr, 9, sizeof(int), compare); 22 int m; 23 for( m = 0; m<9; m++){ 24 if(arr[m] != m+1){ 25 break; 26 } 27 } 28 if(m == 9){ 29 printf("%d %d %d\n",abc, def, ghi); 30 } 31 } 32 return 0; 33 } 34 35 int compare(const void *a, const void *b){ 36 return *(int*)a - *(int*)b; 37 }
