题解 | JZ46 把数字翻译成字符串

class Solution {
public:
    /**
     * 解码
     * @param nums string字符串 数字串
     * @return int整型
     */
    int solve(string nums) {
        // write code here
        int dp[nums.size()];
        memset(dp, 0, sizeof(dp));
        
        if (nums[0] == '0') return 0;
        dp[0] = 1;
        for (int i = 1; i < nums.size(); ++i) {
            if (i == 1) {
                if (nums[i-1] == '1') {
                    if (nums[i] == '0') dp[i] = 1;
                    else dp[i] =2;
                } 
                else if (nums[i-1]=='2') {
                    if (nums[i] <= '6') dp[i] = 2;
                    else dp[i] = 1;
                } else {
                  dp[i] = 1;  
                }
            }
            else {
                if (nums[i] != '0') dp[i] = dp[i-1];
                if (nums[i-1]=='1' || (nums[i-1]=='2' && nums[i] <= '6')) {
                    dp[i] += dp[i-2];
                }
            }
        }
        return dp[nums.size()-1];
    }
};

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 解码
# @param nums string字符串 数字串
# @return int整型
#
class Solution:
    def solve(self , nums: str) -> int:
        # write code here
        dp = [0] * len(nums)
        if nums[0] == '0': return 0
        dp[0] = 1
        
        for i in range(1, len(nums)):
            if i == 1:
                if nums[i-1] == '1':
                    if nums[i] == '0': 
                        dp[i]=1
                    else: 
                        dp[i]=2
                elif nums[i-1] == '2':
                    if nums[i] <= '6':
                        dp[i]=2
                    else:
                        dp[i]=1
                else:
                    dp[i]=1
            else:
                if nums[i] != '0':
                    dp[i] = dp[i-1]
                if (nums[i-1] == '1') or (nums[i-1]=='2' and nums[i] <='6'):
                    dp[i] += dp[i-2]
        
        return dp[len(nums)-1]