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Write a function that takes a string and reverses the letters in place.
In general, an in-place algorithm will require swapping elements.
We swap the first and last characters, then the second and second-to-last characters, and so on until we reach the middle.
void reverse(char *str)
{
size_t rightIndex, leftIndex = 0, strLength = strlen(str);
if (strLength == 0) {
return;
}
rightIndex = strLength - 1;
while (leftIndex < rightIndex) {
// swap characters
char charAtLeftIndex = str[leftIndex];
str[leftIndex] = str[rightIndex];
str[rightIndex] = charAtLeftIndex;
// move towards middle
leftIndex++;
rightIndex--;
}
}
time and space.
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