Light OJ 1110 An Easy LCS (DP+路径记录)

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[code]#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<algorithm>

using namespace std;
typedef pair<int,int> PII;
typedef long long LL;

char s[2][105],tmp[2][105];
int n,m,dp[105][105];
PII pr[105][105];

int bug = 0;

bool cmp(int a1,int b1,int a2,int b2){
int o1,o2,tmp_a,tmp_b;
o1 = o2 = dp[a1][b1];
tmp[0][o1] = tmp[1][o2] = '\0';
while(pr[a1][b1]!=PII(-1,-1)){
if(s[0][a1]==s[1][b1]){
tmp[0][--o1] = s[0][a1];
}
//printf("cmp %d %d %d\n",++bug,a1,b1);
tmp_a = pr[a1][b1].first;
tmp_b = pr[a1][b1].second;
a1 = tmp_a;b1 = tmp_b;
}
while(pr[a2][b2]!=PII(-1,-1)){
if(s[0][a2]==s[1][b2]){
tmp[1][--o2] = s[0][a2];
}
tmp_a = pr[a2][b2].first;
tmp_b = pr[a2][b2].second;
a2 = tmp_a;b2 = tmp_b;
}
return strcmp(tmp[0],tmp[1])<=0;
}

int main(){
int i,j,cas,T;
scanf("%d",&cas);
memset(dp,-1,sizeof(dp));
for(T = 1;T <= cas;T++){
scanf("%s%s",s[0]+1,s[1]+1);
printf("Case %d: ",T);
n = strlen(s[0]+1);
m = strlen(s[1]+1);
memset(dp,0,sizeof(dp));
for(i = 0;i <= n;i++) dp[i][0]=0,pr[i][0] = PII(-1,-1);
for(j = 0;j <= m;j++) dp[0][j]=0,pr[0][j] = PII(-1,-1);
for(i = 1;i <= n;i++){
for(j = 1;j <= m;j++){
//printf("main %d %d %d\n",++bug,i,j);
if(s[0][i]==s[1][j]){
dp[i][j] = dp[i-1][j-1]+1;
pr[i][j] = PII(i-1,j-1);
}else{
dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
if(dp[i][j-1]>dp[i-1][j]){
pr[i][j] = PII(i,j-1);
}else if(dp[i][j-1]<dp[i-1][j]){
pr[i][j] = PII(i-1,j);
}else{
if(cmp(i-1,j,i,j-1)){
pr[i][j] = PII(i-1,j);
}else{
pr[i][j] = PII(i,j-1);
}
}
}
//printf("main %d %d\n",bug,dp[i][j]);
}

}
//printf("%d\n",dp
[m]);
if(dp
[m] == 0){
printf(":(\n");
continue;
}
int a,b,tmp_a,tmp_b,o = dp
[m];
tmp[0][o] = '\0';
a = n,b = m;
while(pr[a][b]!=PII(-1,-1)){
if(s[0][a]==s[1][b]){
tmp[0][--o] = s[0][a];
}
tmp_a = pr[a][b].first;
tmp_b = pr[a][b].second;
a = tmp_a;b = tmp_b;
}
printf("%s\n",tmp[0]);
}

return 0;
}