多校第八场

HDU 4681 String

这道DP题目，赛后我们才A的........比赛中场外孟神怒A之

正向，反向各求最长公共字串一次，然后处理

#include <iostream>#include <algorithm>#include <cmath>#include <cstdio>#include <cstdlib>#include <cstring>#include <string>#include <vector>#include <set>#include <queue>#include <stack>#include <climits>//形如INT_MAX一类的#define MAX 1111#define INF 0x7FFFFFFF#define REP(i,s,t) for(int i=(s);i<=(t);++i)#define ll long long#define mem(a,b) memset(a,b,sizeof(a))#define mp(a,b) make_pair(a,b)#define L(x) x<<1#define R(x) x<<1|1# define eps 1e-5//#pragma comment(linker, "/STACK:36777216") ///传说中的外挂using namespace std;char a[MAX],b[MAX],c[MAX];int dp1[MAX][MAX],dp2[MAX][MAX]; // 前后int pos[MAX*4][2],cnt;int len1,len2,len3;void get(char str[],int len) { //求出loc    int i,j,k;    for(i=1; i<=len; i++) {        if(str[i] == c[1]) {            for(j=i,k=1; j<=len && k<=len3; j ++)                if(str[j] == c[k])                    k++;            if(k != len3+1)                break;            pos[cnt][0] = i;            pos[cnt][1] = j-1;            cnt++;        }    }}void DP1() {    for(int i=1; i<=len1; i++)        for(int j=1; j<=len2; j++) {            if(a[i]==b[j]) dp1[i][j]=dp1[i-1][j-1]+1;            else dp1[i][j]=max(dp1[i-1][j],dp1[i][j-1]);        }}void DP2() {    for(int i=len1; i>=1; i--)        for(int j=len2; j>=1; j--) {            if(a[i]==b[j]) dp2[i][j]=dp2[i+1][j+1]+1;            else dp2[i][j]=max(dp2[i+1][j],dp2[i][j+1]);        }}int main() {    int t,ca = 1;    scanf("%d",&t);    while(t--) {        cnt = 0;        scanf("%s%s%s",a+1,b+1,c+1);        len1=strlen(a+1);        len2=strlen(b+1);        len3=strlen(c+1);        memset(dp1,0,sizeof(dp1));        DP1();        memset(dp2,0,sizeof(dp2));        DP2();        get(a,len1);        int tt = cnt;        get(b,len2);        int y=cnt-tt;        int ans = 0 ;        for(int i=0; i<tt; i++)            for(int j=0; j<y; j++)                ans=max(ans,dp1[pos[i][0]-1][pos[j+tt][0]-1] + dp2[pos[i][1] + 1][pos[j+tt][1] + 1]) ;        printf("Case #%d: %d\n",ca++,ans+len3);    }    return 0;}