31_Next_Permutation.java

classSolution {
publicvoidnextPermutation(int[] nums) {
if (nums == null || nums.length == 0) {
return;
 }

intn = nums.length - 1, idx = -1;

for (inti = n - 1; i >= 0; i--) {
if (nums[i] < nums[i + 1]) {
idx = i;
break;
 }
 }

if (idx == -1) {
reverseArray(nums, 0, n);
return;
 }

for (inti = n; i >= 0; i--) {
if (nums[i] > nums[idx]) {
swap(nums, i, idx);
break;
 }
 }

reverseArray(nums, idx + 1, n);
 }

privatevoidreverseArray(int[] nums, intstart, intend) {
while (start < end) {
swap(nums, start, end);
 ++start;
 --end;
 }
 }

privatevoidswap(int[] nums, inti, intj) {
inttemp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
 }
}