Decode Ways

最新推荐文章于 2021-02-16 21:52:55 发布

sjphiChina

最新推荐文章于 2021-02-16 21:52:55 发布

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分类专栏：刷遍数

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array[0] = 1;

初始值是1

public class Solution {
    public int numDecodings(String s) {
        if (s == null) {
<span style="white-space:pre">			</span>throw new IllegalArgumentException("");
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>if (s.length() == 0) {
<span style="white-space:pre">			</span>return 0;
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>int [] array = new int[s.length() + 1];
<span style="white-space:pre">		</span>array[0] = 1;
<span style="white-space:pre">		</span>array[1] = s.charAt(0) == '0' ? 0 : 1;
<span style="white-space:pre">		</span>for (int i = 2; i <= s.length(); i++) {
<span style="white-space:pre">			</span>if (s.charAt(i - 1) != '0') {
<span style="white-space:pre">				</span>array[i] = array[i - 1];
<span style="white-space:pre">			</span>}
<span style="white-space:pre">			</span>int twoDigits = (s.charAt(i - 2) - '0')*10 + (s.charAt(i - 1) - '0');
<span style="white-space:pre">			</span>if (twoDigits >= 10 && twoDigits <= 26) {
<span style="white-space:pre">				</span>array[i] = array[i - 2] + array[i];
<span style="white-space:pre">			</span>}
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>return array[s.length()];
    }
}