dp
f(i, j)表示text1[0...i)和text2[0...j)的公共字符串
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| class Solution {
public:
int longestCommonSubsequence(string text1, string text2) {
int m = text1.size(), n = text2.size();
vector<vector<int>> dp(m + 1, vector<int>(n + 1));
for(int i = 1; i <= m; ++i)
{
for(int j = 1; j <= n; ++j)
{
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]);
}
}
return dp.back().back();
}
};
|
优化空间
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| class Solution {
public:
int longestCommonSubsequence(string text1, string text2) {
int m = text1.size(), n = text2.size();
vector<int> dp(n + 1);
int tmp = 0;
for(int i = 1; i <= m; ++i)
{
tmp = 0;
for(int j = 1; j <= n; ++j)
{
int pre = dp[j];
if(text1[i - 1] == text2[j - 1])
dp[j] = tmp + 1;
else
dp[j] = max(dp[j], dp[j - 1]);
tmp = pre;
}
}
return dp.back();
}
};
|