紫书动规 例题9-8 UVA - 1625 Color Length dp

题目链接:

题意:

题解:

代码:

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define MS(a) memset(a,0,sizeof(a))
#define MP make_pair
#define PB push_back
const int INF = 0x3f3f3f3f;
const ll INFLL = 0x3f3f3f3f3f3f3f3fLL;
inline ll read(){
ll x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
//////////////////////////////////////////////////////////////////////////
const int maxn = 5e3+10;

int n,m;
char a[maxn],b[maxn];
int bg[maxn][2],ed[maxn][2],w[maxn][maxn];
int dp[maxn][maxn],f[maxn][maxn];

int main(){
int T = read();
while(T--){
scanf("%s%s",a+1,b+1);
n=strlen(a+1),m=strlen(b+1);
for(int i=0; i<=26; i++) bg[i][0]=bg[i][1] = INF;
for(int i=0; i<=26; i++) ed[i][0]=ed[i][1] = 0;
for(int i=1; i<=n; i++){
int c = a[i]-'A';
if(bg[c][0] == INF) bg[c][0] = i;
ed[c][0] = i;
}
for(int i=1; i<=m; i++){
int c = b[i]-'A';
if(bg[c][1] == INF) bg[c][1] = i;
ed[c][1] = i;
}

for(int i=0; i<=n; i++){
for(int j=0; j<=m; j++){
if(!i && !j) continue;

int t1 = INF, t2 = INF;
if(i>0) t1 = dp[i-1][j]+w[i-1][j];
if(j>0) t2 = dp[i][j-1]+w[i][j-1];
dp[i][j] = min(t1,t2);

if(i > 0){
w[i][j] = w[i-1][j];
int c = a[i] - 'A';
if(bg[c][0]==i && bg[c][1]>j) w[i][j]++;
if(ed[c][0]==i && ed[c][1]<=j) w[i][j]--;
}else{
w[i][j] = w[i][j-1];
int c = b[j] - 'A';
if(bg[c][1]==j && bg[c][0]>i) w[i][j]++;
if(ed[c][1]==j && ed[c][0]<=i) w[i][j]--;
}
}
}

cout << dp
[m] << endl;

}

return 0;
}

// http://www.cnblogs.com/candy99/p/5985217.html[/code]