题解 | 把数字翻译成字符串

class Solution {
public:
    /**
     * 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
     */
    int solve(string nums) {
        int n = nums.size();
        if (n == 0 || nums[0] == '0') return 0;

        int prev1 = 1, prev2 = 1;

        for (int i = 2; i <= n; i++) {
            int cur = 0;
            char one = nums[i - 1], two = nums[i - 2];
            
            if (one >= '1' && one <= '9') cur += prev1;
            int num = (two - '0') * 10 + (one - '0');
            if (num >= 10 && num <= 26) cur += prev2;
            
            prev2 = prev1, prev1 = cur;
        }
        return prev1;
    }
};