Best shuffle: Difference between revisions

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=={{header|D}}==

<lang d>int bestShuffle(~~string~~ s) {

<lang d>int bestShuffle(char[] s1) {

int countSamePositions(T, ~~U)(T~~ s1, U s2) {

int countSamePositions(char[] r1, char[] r2, int len) {

int count;

return count!("a[0] == a[1] && a[0] != b")(zip(s1, s2), '-');

for (int i; i < len; i++) {

if (r2[i] != '-' && r1[i] == r2[i]) {

count++;

}

⚫

}

return count;

}

const len = s.length;

const len = s1.length;

if ~~(len~~ =~~= 0)~~ {

char[] s2 = s1.dup;

throw new Exception("input string cannot have zero length");

⚫

}

~~char[]~~ ch = ~~s.dup.sort;~~

if (len < 3) {

s2.reverse;

⚫

} else {

s2.sort;

auto problemChar = sort!("a[1] > b[1]")(array(group(ch)))[0];

auto problemChar = sort!("a[1] > b[1]")(array(group(s2)))[0];

if ((problemChar[1] - len / 2) > 0) {

int numToRemove = problemChar[1] - (len - problemChar[1]);

for (int i, j; i < len && j < numToRemove; i++) {

if (ch[i] == problemChar[0]) {

if (s2[i] == problemChar[0]) {

ch[i] = '-';

s2[i] = '-';

j++;

}

do {

for (int i = len; i > 1; i--) {

⚫

do {

~~for~~ ~~(int~~ i = ~~len;~~ i > 1; i--) {

swap(s2[i-1], s2[uniform(0, i)]);

~~swap(ch[i-1], ch[uniform(0, i)]);~~

}

⚫

} while(countSamePositions(s1, s2, len) > 0);

char pc = cast(char)problemChar[0];

for (int i; i < len; i++) {

if (s2[i] == '-') {

s2[i] = pc;

}

⚫

} while(countSamePositions(s, ch) > 0);

string result = replace(to!string(ch), "-", to!string(problemChar[0]));

⚫

int samePos = countSamePositions(s, ~~result~~);

⚫

int samePos = countSamePositions(s1, s2, len);

writefln("%s %s (%s)", s, ~~result~~, samePos);

writefln("%s %s (%s)", s1, s2, samePos);

return samePos;

}</lang>

output:<pre>abracadabra ~~baadacbraar~~ (0)

output:<pre>abracadabra caararbdaab (0)

seesaw ~~easwes~~ (0)

seesaw essawe (0)

elk lke (0)

grrrrrr rrrrrgr (5)

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<lang d>unittest {

assert(bestShuffle("abracadabra") == 0);

assert(bestShuffle("abracadabra".dup) == 0);

assert(bestShuffle("seesaw") == 0);

assert(bestShuffle("seesaw".dup) == 0);

assert(bestShuffle("elk") == 0);

assert(bestShuffle("elk".dup) == 0);

assert(bestShuffle("grrrrrr") == 5);

assert(bestShuffle("grrrrrr".dup) == 5);

assert(bestShuffle("up") == 0);

assert(bestShuffle("up".dup) == 0);

assert(bestShuffle("a") == 1);

assert(bestShuffle("a".dup) == 1);

}</lang>