There are 1, 2, 3, 4 digits, how many different and no repetition of the number of three digits? How much are they?

Title: There are 1,2,3,4 numbers, can make up how many different and no repetition of the number of three digits? How much are they?

Solution: Program Analysis: Can be filled in hundreds, 10 digits, single digit numbers are 1,2,3,4 . Make all the permutations and then remove the permutations that do not meet the criteria.

Program:

#include <stdio.h>

int main ()

{

int i = 0, j = 0, k = 0,count=0;

for (i = 1; i < 5; i++)

{

for (j = 1; j < 5; J + +)

{

for (k = 1; k < 5; k++)

{

if ((i! = j) && (i! = k) && (J! = k))

{

count++;

printf ("%d%d%d\n", I, J, K);

}

}

}

}

printf ("count=%d\n", count);

System ("pause");

return 0;

}

Operation Result:

123

124

132

134

142

143

213

214

231

234

241

243

312

314

321

324

341

342

412

413

421

423

431

432

Count=24

Please press any key to continue ...

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There are 1, 2, 3, 4 digits, how many different and no repetition of the number of three digits? How much are they?