DFS:
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
using namespace std;
const int maxn = 1000 + 10;
char a[maxn],b[maxn];
int dp[maxn][maxn];
int main(){
while(scanf("%s %s",a,b) != EOF){
int n = strlen(a);
int m = strlen(b);
for(int i = 0;i<n;i++){
for(int j = 0;j<m;j++){
if(a[i] == b[j]){
if(dp[i][j] + 1 > max(dp[i+1][j],dp[i][j+1]))//用dp[i+1][j+1]来记录a前i个和b前j个
{
dp[i+1][j+1] = dp[i][j] + 1;
}
else dp[i+1][j+1] = max(dp[i+1][j],dp[i][j+1]);
}
else
dp[i+1][j+1] = max(dp[i+1][j],dp[i][j+1]);
}
}
printf("%d\n",dp[n][m]);
}
}
DFS加路径:
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<stack>
using namespace std;
const int maxn = 1000 + 10;
char a[maxn],b[maxn];
int dp[maxn][maxn];
int n,m;
void lcs(){
for(int i = 0;i<n;i++){
for(int j = 0;j<m;j++){
if(a[i] == b[j]){
// if(dp[i][j] + 1 > max(dp[i+1][j],dp[i][j+1]))////用dp[i+1][j+1]来记录a前i个和b前j个
// {
// dp[i+1][j+1] = dp[i][j] + 1;
// }
// else dp[i+1][j+1] = max(dp[i+1][j],dp[i][j+1]);
dp[i+1][j+1] = dp[i][j] + 1;
}
else
dp[i+1][j+1] = max(dp[i+1][j],dp[i][j+1]);
}
}
}
stack<char> road;
int main(){
scanf("%s %s",a,b);
n = strlen(a),m = strlen(b);
lcs();
int ii = n,jj = m;
while(dp[ii][jj]){
if(dp[ii][jj] == dp[ii][jj-1]) jj--;
else if(dp[ii][jj] == dp[ii-1][jj]) ii--;
else{
ii--,jj--;
road.push(a[ii]);//ii-1记录的是 a[ii]
//ii--,jj--;
}
}
while(!road.empty()){
printf("%c",road.top());
road.pop();
}
return 0;
}
DFS记录路径2:
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<stack>
using namespace std;
const int maxn = 1000 + 10;
char a[maxn],b[maxn];
int dp[maxn][maxn];
int n,m;
int road[maxn][maxn];
void lcs(){
for(int i = 0;i<n;i++){
for(int j = 0;j<m;j++){
if(a[i] == b[j]){
// if(dp[i][j] + 1 > max(dp[i+1][j],dp[i][j+1]))////用dp[i+1][j+1]来记录a前i个和b前j个
// {
// dp[i+1][j+1] = dp[i][j] + 1;
// }
// else dp[i+1][j+1] = max(dp[i+1][j],dp[i][j+1]);
dp[i+1][j+1] = dp[i][j] + 1;
road[i+1][j+1] = 1;
}
else {
if(dp[i+1][j] > dp[i][j+1]){
road[i+1][j+1] = 2;
dp[i+1][j+1] = dp[i+1][j];
}
else{
road[i+1][j+1] = 3;
dp[i+1][j+1] = dp[i][j+1];
}
}
}
}
}
stack<char> ro;
char vis[maxn];
int main(){
scanf("%s %s",a,b);
n = strlen(a),m = strlen(b);
lcs();
int ii = n,jj = m;
memset(road,0,sizeof(road));
// int i = 0;
while(dp[ii][jj]){
if(road[ii][jj] == 3) jj--;
else if(road[ii][jj] == 2) ii--;
else{
ii--,jj--;
ro.push(a[ii]);//ii-1记录的是 a[ii]
//ii--,jj--;
}
}
while(!ro.empty()){
printf("%c",ro.top());
ro.pop();
}
return 0;
}