Update Next Permutation.java

varunu28 · web-flow · commit 9d4b55bc1e61 · 2022-08-09T16:23:09.000-07:00
diff --git a/Medium/Next Permutation.java b/Medium/Next Permutation.java
@@ -1,10 +1,7 @@
 class Solution {
   public void nextPermutation(int[] nums) {
-    if (nums.length <= 1) {
-      return;
-    }
     int idx = nums.length - 2;
-    while (idx >= 0 && nums[idx] >= nums[idx + 1]) {
+    while (idx >= 0 && nums[idx + 1] <= nums[idx]) {
       idx--;
     }
     if (idx >= 0) {
@@ -14,16 +11,21 @@ public void nextPermutation(int[] nums) {
       }
       swap(nums, idx, endIdx);
     }
-    int startIdx = idx + 1;
+    reverse(nums, idx + 1);
+  }
+  
+  private void reverse(int[] nums, int startIdx) {
     int endIdx = nums.length - 1;
     while (startIdx < endIdx) {
-      swap(nums, startIdx++, endIdx--);
+      swap(nums, startIdx, endIdx);
+      startIdx++;
+      endIdx--;
     }
   }
   
-  private void swap(int[] nums, int idxOne, int idxTwo) {
-    int temp = nums[idxOne];
-    nums[idxOne] = nums[idxTwo];
-    nums[idxTwo] = temp;
+  private void swap(int[] nums, int i, int j) {
+    int temp = nums[i];
+    nums[i] = nums[j];
+    nums[j] = temp;
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -1,10 +1,7 @@`
`1`	`1`	`class Solution {`
`2`	`2`	`public void nextPermutation(int[] nums) {`
`3`		`- if (nums.length <= 1) {`
`4`		`- return;`
`5`		`- }`
`6`	`3`	`int idx = nums.length - 2;`
`7`		`- while (idx >= 0 && nums[idx] >= nums[idx + 1]) {`
	`4`	`+ while (idx >= 0 && nums[idx + 1] <= nums[idx]) {`
`8`	`5`	`idx--;`
`9`	`6`	`}`
`10`	`7`	`if (idx >= 0) {`
`@@ -14,16 +11,21 @@ public void nextPermutation(int[] nums) {`
`14`	`11`	`}`
`15`	`12`	`swap(nums, idx, endIdx);`
`16`	`13`	`}`
`17`		`- int startIdx = idx + 1;`
	`14`	`+ reverse(nums, idx + 1);`
	`15`	`+ }`
	`16`	`+`
	`17`	`+ private void reverse(int[] nums, int startIdx) {`
`18`	`18`	`int endIdx = nums.length - 1;`
`19`	`19`	`while (startIdx < endIdx) {`
`20`		`- swap(nums, startIdx++, endIdx--);`
	`20`	`+ swap(nums, startIdx, endIdx);`
	`21`	`+ startIdx++;`
	`22`	`+ endIdx--;`
`21`	`23`	`}`
`22`	`24`	`}`
`23`	`25`
`24`		`- private void swap(int[] nums, int idxOne, int idxTwo) {`
`25`		`- int temp = nums[idxOne];`
`26`		`- nums[idxOne] = nums[idxTwo];`
`27`		`- nums[idxTwo] = temp;`
	`26`	`+ private void swap(int[] nums, int i, int j) {`
	`27`	`+ int temp = nums[i];`
	`28`	`+ nums[i] = nums[j];`
	`29`	`+ nums[j] = temp;`
`28`	`30`	`}`
`29`	`31`	`}`