405 最长公共子序列 线性DP

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

const int N=1010;
int n, m;
char a[N], b[N];
int f[N][N];

int main(){
  cin>>n>>m>>a+1>>b+1;
  
  for(int i=1; i<=n; i++)
    for(int j=1; j<=m; j++)
      if(a[i]==b[j]) f[i][j]=f[i-1][j-1]+1;
      else f[i][j]=max(f[i-1][j-1],max(f[i-1][j],f[i][j-1]));
  
  cout<<f[n][m];
}