题目
Given a non-negative integer represented as a non-empty array of digits, plus one to the integer.
You may assume the integer do not contain any leading zero, except the number 0 itself.
The digits are stored such that the most significant digit is at the head of the list.
老老实实遍历数组
这题就是老老实实一位一位加，进位。唯一需要增加数组长度的情况是99+1=100这样。
第一版代码
public class Solution {
public int[] plusOne(int[] digits) {
int carry = 1;
for (int i = digits.length-1; i >= 0 && carry == 1; i--) {
int sum = digits[i] + carry;
digits[i] = sum % 10;
carry = sum / 10;
}
if (carry == 1) { // 唯一需要增加数组长度的情况
digits = new int[digits.length+1];
digits[0] = 1;
}
return digits;
}
}
理清思路，优化版
public int[] plusOne(int[] digits) {
for (int i = digits.length-1; i >=0; i--) {
if (digits[i] < 9) {
digits[i]++; break;
} else {
digits[i] = 0;
}
}
if (digits[0] == 0) {
digits = new int[digits.length+1];
digits[0] = 1;
}
return digits;
}
结果
