There is C code below my professor wants me to implement different methodss of generating all N! permutations of N elements in JAVA!! This has to be in java. Could someone please help me convert his c code to java code and add comments for me to understand the steps

#include #include #include

#define MILLION 1000000L

unsigned N; char P[27]; unsigned table[12][12] = { {0}, {0, 1}, {0, 1, 1}, {0, 1, 2, 3}, {0, 3, 1, 3, 1}, {0, 3, 4, 3, 2, 3}, {0, 5, 3, 1, 5, 3, 1}, {0, 5, 2, 7, 2, 1, 2, 3}, {0, 7, 1, 5, 5, 3, 3, 7, 1}, {0, 7, 8, 1, 6, 5, 4, 9, 2, 3}, {0, 9, 7, 5, 3, 1, 9, 7, 5, 3, 1}, {0, 9, 6, 3, 10, 9, 4, 3, 8, 9, 2, 3}};

void init(void){ unsigned i;

P[0] = '*'; for (i=0; i<26; i++) P[i+1] = 'A' + i; }

inline void swap(unsigned i, unsigned j){ char c;

c = P[i]; P[i] = P[j]; P[j] = c; }

void printIt(void){ static unsigned long count = 0;

//to compare performance, comment out from here unsigned i;

for (i=1; i<=N; i++) printf("%c", P[i]); printf(" "); //to here

count++; }

void permute1(unsigned n){ unsigned i;

if (n == 1) printIt(); for (i=1; i<=n; i++){ swap(i, n); permute1(n-1); swap(i, n); } }

void permute2(unsigned n){ unsigned i;

if (n == 1){ printIt(); return; } for (i=1; i<=n; i++){ permute2(n - 1); swap(table[n][i], n); } }

void permute3(unsigned n){ unsigned i;

if (n == 1){ printIt(); return; } for (i=1; i<=n; i++){ permute3(n - 1); swap((n & 0x01) ? 1 : i, n); } }

void (*algPtr[4])(unsigned) = {NULL, permute1, permute2, permute3};

int main(int argc, char *argv[]){ unsigned alg; int c;

N = 4; alg = 1; while ((c = getopt(argc, argv, "a:n:")) != -1){ switch (c){ case 'a': sscanf(optarg, "%u", &alg); break; case 'n': sscanf(optarg, "%u", &N); break; default: break; } } N = ((N < 2) || (N > 12)) ? 4 : N; alg = ((alg < 1) || (alg > 3)) ? 1 : alg;

init();

struct timeval start, stop; float sec;

gettimeofday(&start, NULL); algPtr[alg](N); gettimeofday(&stop, NULL);

sec = (stop.tv_sec - start.tv_sec) + (stop.tv_usec - start.tv_usec) / (float)MILLION; printf("permute%1d, N = %u, %.6f ", alg, N, sec);

return 0; }