[LeetCode] 66. Plus One 加一运算

Given a non-empty array of decimal digits representing a non-negative integer, increment one to the integer.

The digits are stored such that the most significant digit is at the head of the list, and each element in the array contains a single digit.

You may assume the integer does not contain any leading zero, except the number 0 itself.

Example 1:

Input: digits = [1,2,3]
Output: [1,2,4]
Explanation: The array represents the integer 123.


Example 2:

Input: digits = [4,3,2,1]
Output: [4,3,2,2]
Explanation: The array represents the integer 4321.


Example 3:

Input: digits = [0]
Output: [1]


Constraints:

• 1 <= digits.length <= 100
• 0 <= digits[i] <= 9

C++ 解法一：

class Solution {
public:
vector<int> plusOne(vector<int> &digits) {
int n = digits.size();
for (int i = n - 1; i >= 0; --i) {
if (digits[i] == 9) digits[i] = 0;
else {
digits[i] += 1;
return digits;
}
}
if (digits.front() == 0) digits.insert(digits.begin(), 1);
return digits;
}
};

Java 解法一：

public class Solution {
public int[] plusOne(int[] digits) {
int n = digits.length;
for (int i = digits.length - 1; i >= 0; --i) {
if (digits[i] < 9) {
++digits[i];
return digits;
}
digits[i] = 0;
}
int[] res = new int[n + 1];
res[0] = 1;
return res;
}
}

C++ 解法二 ：

class Solution {
public:
vector<int> plusOne(vector<int>& digits) {
if (digits.empty()) return digits;
int carry = 1, n = digits.size();
for (int i = n - 1; i >= 0; --i) {
if (carry == 0) return digits;
int sum = digits[i] + carry;
digits[i] = sum % 10;
carry = sum / 10;
}
if (carry == 1) digits.insert(digits.begin(), 1);
return digits;
}
};

Java 解法二 ：

public class Solution {
public int[] plusOne(int[] digits) {
if (digits.length == 0) return digits;
int carry = 1, n = digits.length;
for (int i = digits.length - 1; i >= 0; --i) {
if (carry == 0) return digits;
int sum = digits[i] + carry;
digits[i] = sum % 10;
carry = sum / 10;
}
int[] res = new int[n + 1];
res[0] = 1;
return carry == 0 ? digits : res;
}
}

Github 同步地址：

https://github.com/grandyang/leetcode/issues/66

Multiply Strings

https://leetcode.com/problems/plus-one/

https://leetcode.com/problems/plus-one/discuss/24082/my-simple-java-solution

https://leetcode.com/problems/plus-one/discuss/24084/Is-it-a-simple-code(C%2B%2B)

LeetCode All in One 题目讲解汇总(持续更新中...)

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posted @ 2014-11-06 17:01  Grandyang  阅读(20426)  评论(2编辑  收藏  举报