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solution/1000-1099/1013.Partition Array Into Three Parts With Equal Sum
6 files changed +317
-2
lines changed Original file line number Diff line number Diff line change 4848
4949<!-- 这里可写通用的实现逻辑 -->
5050
51+ ** 方法一：双指针**
52+
53+ 先遍历数组 ` arr ` ，得到数组所有元素的和，记为 ` s ` 。如果 ` s ` 不能被 3 整除，那么数组 ` arr ` 不能被分成和相等的三个部分，直接返回 ` false ` 。
54+
55+ 接下来，利用双指针 ` i ` , ` j ` 找三等分和的边界，若成功找到，返回 ` true ` ，否则返回 ` false ` 。
56+
57+ 时间复杂度 $O(n)$，空间复杂度 $O(1)$，其中 $n$ 为数组 ` arr ` 的长度。
58+
5159<!-- tabs:start -->
5260
5361### ** Python3**
5462
5563<!-- 这里可写当前语言的特殊实现逻辑 -->
5664
5765``` python
58-
66+ class Solution :
67+ def canThreePartsEqualSum (self arr : List[int ]) -> bool :
68+ s = sum (arr)
69+ if s % 3 != 0 :
70+ return False
71+ i, j = 0 , len (arr) - 1
72+ a = b = 0
73+ while i < len (arr):
74+ a += arr[i]
75+ if a == s // 3 :
76+ break
77+ i += 1
78+ while ~ j:
79+ b += arr[j]
80+ if b == s // 3 :
81+ break
82+ j -= 1
83+ return i < j - 1
5984```
6085
6186### ** Java**
6287
6388<!-- 这里可写当前语言的特殊实现逻辑 -->
6489
6590``` java
91+ class Solution {
92+ public boolean canThreePartsEqualSum (int [] arr ) {
93+ int s = 0 ;
94+ for (int v : arr) {
95+ s += v;
96+ }
97+ if (s % 3 != 0 ) {
98+ return false ;
99+ }
100+ int i = 0 , j = arr. length - 1 ;
101+ int a = 0 , b = 0 ;
102+ while (i < arr. length) {
103+ a += arr[i];
104+ if (a == s / 3 ) {
105+ break ;
106+ }
107+ ++ i;
108+ }
109+ while (j >= 0 ) {
110+ b += arr[j];
111+ if (b == s / 3 ) {
112+ break ;
113+ }
114+ -- j;
115+ }
116+ return i < j - 1 ;
117+ }
118+ }
119+ ```
120+
121+ ### ** C++**
122+
123+ ``` cpp
124+ class Solution {
125+ public:
126+ bool canThreePartsEqualSum(vector<int >& arr) {
127+ int s = 0;
128+ for (int v : arr) s += v;
129+ if (s % 3) return false;
130+ int i = 0, j = arr.size() - 1;
131+ int a = 0, b = 0;
132+ while (i < arr.size()) {
133+ a += arr[ i] ;
134+ if (a == s / 3) {
135+ break;
136+ }
137+ ++i;
138+ }
139+ while (~ j) {
140+ b += arr[ j] ;
141+ if (b == s / 3) {
142+ break;
143+ }
144+ --j;
145+ }
146+ return i < j - 1;
147+ }
148+ };
149+ ```
66150
151+ ### **Go**
152+
153+ ```go
154+ func canThreePartsEqualSum(arr []int) bool {
155+ s := 0
156+ for _, v := range arr {
157+ s += v
158+ }
159+ if s%3 != 0 {
160+ return false
161+ }
162+ i, j := 0, len(arr)-1
163+ a, b := 0, 0
164+ for i < len(arr) {
165+ a += arr[i]
166+ if a == s/3 {
167+ break
168+ }
169+ i++
170+ }
171+ for j >= 0 {
172+ b += arr[j]
173+ if b == s/3 {
174+ break
175+ }
176+ j--
177+ }
178+ return i < j-1
179+ }
67180```
68181
69182### ** ...**
Original file line number Diff line number Diff line change 4747### ** Python3**
4848
4949``` python
50-
50+ class Solution :
51+ def canThreePartsEqualSum (self arr : List[int ]) -> bool :
52+ s = sum (arr)
53+ if s % 3 != 0 :
54+ return False
55+ i, j = 0 , len (arr) - 1
56+ a = b = 0
57+ while i < len (arr):
58+ a += arr[i]
59+ if a == s // 3 :
60+ break
61+ i += 1
62+ while ~ j:
63+ b += arr[j]
64+ if b == s // 3 :
65+ break
66+ j -= 1
67+ return i < j - 1
5168```
5269
5370### ** Java**
5471
5572``` java
73+ class Solution {
74+ public boolean canThreePartsEqualSum (int [] arr ) {
75+ int s = 0 ;
76+ for (int v : arr) {
77+ s += v;
78+ }
79+ if (s % 3 != 0 ) {
80+ return false ;
81+ }
82+ int i = 0 , j = arr. length - 1 ;
83+ int a = 0 , b = 0 ;
84+ while (i < arr. length) {
85+ a += arr[i];
86+ if (a == s / 3 ) {
87+ break ;
88+ }
89+ ++ i;
90+ }
91+ while (j >= 0 ) {
92+ b += arr[j];
93+ if (b == s / 3 ) {
94+ break ;
95+ }
96+ -- j;
97+ }
98+ return i < j - 1 ;
99+ }
100+ }
101+ ```
102+
103+ ### ** C++**
104+
105+ ``` cpp
106+ class Solution {
107+ public:
108+ bool canThreePartsEqualSum(vector<int >& arr) {
109+ int s = 0;
110+ for (int v : arr) s += v;
111+ if (s % 3) return false;
112+ int i = 0, j = arr.size() - 1;
113+ int a = 0, b = 0;
114+ while (i < arr.size()) {
115+ a += arr[ i] ;
116+ if (a == s / 3) {
117+ break;
118+ }
119+ ++i;
120+ }
121+ while (~ j) {
122+ b += arr[ j] ;
123+ if (b == s / 3) {
124+ break;
125+ }
126+ --j;
127+ }
128+ return i < j - 1;
129+ }
130+ };
131+ ```
56132
133+ ### **Go**
134+
135+ ```go
136+ func canThreePartsEqualSum(arr []int) bool {
137+ s := 0
138+ for _, v := range arr {
139+ s += v
140+ }
141+ if s%3 != 0 {
142+ return false
143+ }
144+ i, j := 0, len(arr)-1
145+ a, b := 0, 0
146+ for i < len(arr) {
147+ a += arr[i]
148+ if a == s/3 {
149+ break
150+ }
151+ i++
152+ }
153+ for j >= 0 {
154+ b += arr[j]
155+ if b == s/3 {
156+ break
157+ }
158+ j--
159+ }
160+ return i < j-1
161+ }
57162```
58163
59164### ** ...**
Original file line number Diff line number Diff line change 1+ class Solution {
2+ public:
3+ bool canThreePartsEqualSum (vector<int >& arr) {
4+ int s = 0 ;
5+ for (int v : arr) s += v;
6+ if (s % 3 ) return false ;
7+ int i = 0 , j = arr.size () - 1 ;
8+ int a = 0 , b = 0 ;
9+ while (i < arr.size ()) {
10+ a += arr[i];
11+ if (a == s / 3 ) {
12+ break ;
13+ }
14+ ++i;
15+ }
16+ while (~j) {
17+ b += arr[j];
18+ if (b == s / 3 ) {
19+ break ;
20+ }
21+ --j;
22+ }
23+ return i < j - 1 ;
24+ }
25+ };
Original file line number Diff line number Diff line change 1+ func canThreePartsEqualSum (arr []int ) bool {
2+ s := 0
3+ for _ , v := range arr {
4+ s += v
5+ }
6+ if s % 3 != 0 {
7+ return false
8+ }
9+ i , j := 0 , len (arr )- 1
10+ a , b := 0 , 0
11+ for i < len (arr ) {
12+ a += arr [i ]
13+ if a == s / 3 {
14+ break
15+ }
16+ i ++
17+ }
18+ for j >= 0 {
19+ b += arr [j ]
20+ if b == s / 3 {
21+ break
22+ }
23+ j --
24+ }
25+ return i < j - 1
26+ }
Original file line number Diff line number Diff line change 1+ class Solution {
2+ public boolean canThreePartsEqualSum (int [] arr ) {
3+ int s = 0 ;
4+ for (int v : arr ) {
5+ s += v ;
6+ }
7+ if (s % 3 != 0 ) {
8+ return false ;
9+ }
10+ int i = 0 , j = arr .length - 1 ;
11+ int a = 0 , b = 0 ;
12+ while (i < arr .length ) {
13+ a += arr [i ];
14+ if (a == s / 3 ) {
15+ break ;
16+ }
17+ ++i ;
18+ }
19+ while (j >= 0 ) {
20+ b += arr [j ];
21+ if (b == s / 3 ) {
22+ break ;
23+ }
24+ --j ;
25+ }
26+ return i < j - 1 ;
27+ }
28+ }
Original file line number Diff line number Diff line change 1+ class Solution :
2+ def canThreePartsEqualSum (self , arr : List [int ]) -> bool :
3+ s = sum (arr )
4+ if s % 3 != 0 :
5+ return False
6+ i , j = 0 , len (arr ) - 1
7+ a = b = 0
8+ while i < len (arr ):
9+ a += arr [i ]
10+ if a == s // 3 :
11+ break
12+ i += 1
13+ while ~ j :
14+ b += arr [j ]
15+ if b == s // 3 :
16+ break
17+ j -= 1
18+ return i < j - 1
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