------
## 最终结论
```python
def longest_common_subsequence(text1, text2):
    # 初始化DP数组
    dp = [[0] * (len(text2) + 1) for _ in range(len(text1) + 1)]
    
    # 填充DP数组
    for i in range(1, len(text1) + 1):
        for j in range(1, len(text2) + 1):
            if text1[i - 1] == text2[j - 1]:
                dp[i][j] = dp[i - 1][j - 1] + 1
            else:
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])
    
    # 返回结果
    return dp[len(text1)][len(text2)]
```