【CodeForces】471D MUH and Cube Walls KMP或者字符串HASH

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想到两点就行：
1、相邻项相减，处理出相对高度，这样如果pattern或者text增加的话，就没问题了

2、KMP匹配O(n)

HASH的话 ，我WA在第25组数据了，听说如果改为大素数取模就能AC

KMP AC了 但是好奇怪我的KMP模板难道有问题？？

先贴KMP ac 代码

//#pragma comment(linker, "/STACK:102400000,102400000")
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <iostream>
#include <iomanip>
#include <cmath>
#include <map>
#include <set>
#include <queue>
using namespace std;

#define ls(rt) rt*2
#define rs(rt) rt*2+1
#define ll long long
#define ull unsigned long long
#define rep(i,s,e) for(int i=s;i<e;i++)
#define repe(i,s,e) for(int i=s;i<=e;i++)
#define CL(a,b) memset(a,b,sizeof(a))
#define IN(s) freopen(s,"r",stdin)
#define OUT(s) freopen(s,"w",stdout)
const ll ll_INF = ((ull)(-1))>>1;
const double EPS = 1e-8;
const double pi = acos(-1.0);
const int INF = 100000000;
const int MAXN = 2*1e5+50;
const ull B = 1e8+7;

//ll a[MAXN],b[MAXN];
//const int MAXN = 1000+10;
ll T[MAXN],P[MAXN];//T--文本，P--模板串
int fail[MAXN];
int n,w;
void getfail()
{
    int m=w;
    fail[0]=fail[1]=0;
    for(int i=1;i<m;i++)
    {
        int j=fail[i];
        while(j && P[i]!=P[j])j=fail[j];
        fail[i+1]=P[i]==P[j]?j+1:0;
    }
}

int Find()
{
    //int n=strlen(T),m=strlen(P);
    int m=w,ret=0;
    if(w>n)return 0;
    getfail();
    int j=0;
    for(int i=0;i<=n;i++)/// i<n WA??为什么？？
    {
        while(j && P[j]!=T[i])j=fail[j];
        if(P[j] == T[i])j++;
        if(j==m)//printf("%d\n",i-m+1);//find it
        {
            //j = fail[j];///////
            ret++;
        }
    }
    return ret;
}


int main()
{
    //IN("D.txt");
    //init();
    while(~scanf("%d%d",&n,&w))
    {
       for(int i=0;i<n;i++)
            scanf("%I64d",&T[i]);
        for(int i=0;i<w;i++)
            scanf("%I64d",&P[i]);
       for(int i=0;i<n-1;i++)
            T[i]=T[i+1]-T[i]+2*1e9;//,printf("%I64d ",T[i]);
       for(int i=0;i<w-1;i++)
            P[i]=P[i+1]-P[i]+2*1e9;
        if(w==1)P[0]=2*1e9;
        w--,n--;
        printf("%d\n",Find());
    }
    return 0;
}

//#pragma comment(linker, "/STACK:102400000,102400000")
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <iostream>
#include <iomanip>
#include <cmath>
#include <map>
#include <set>
#include <queue>
using namespace std;

#define ls(rt) rt*2
#define rs(rt) rt*2+1
#define ll long long
#define ull unsigned long long
#define rep(i,s,e) for(int i=s;i<e;i++)
#define repe(i,s,e) for(int i=s;i<=e;i++)
#define CL(a,b) memset(a,b,sizeof(a))
#define IN(s) freopen(s,"r",stdin)
#define OUT(s) freopen(s,"w",stdout)
const ll ll_INF = ((ull)(-1))>>1;
const double EPS = 1e-8;
const double pi = acos(-1.0);
const int INF = 100000000;
const int MAXN = 2*1e5+50;
const ull B = 1e8+7;

ll a[MAXN],b[MAXN], aa[MAXN],bb[MAXN];
ull base[MAXN];
//ha[MAXN],hb[MAXN],
int n,w;

void init()
{
    base[0]=1;
    for(int i=1;i<MAXN;i++)
        base[i]=base[i-1]*B;
}

int solve()
{
    int ret=0;
    if(w>n)return 0;
    ull ha=0,hb=0,t=1;
    for(int i=1;i<w;i++)
        hb=hb*B+b[i],ha=ha*B+a[i],t*=B;

    for(int i=1;i+w-1<=n;i++)
    {
        if(ha == hb )ret++;//,cout << i << endl;
        ha=ha*B + a[i+w-1] -a[i]*t;
    }

    return ret;
}

int main()
{
    //IN("D.txt");
    //init();
    while(~scanf("%d%d",&n,&w))
    {
       for(int i=0;i<n;i++)
            scanf("%I64d",&aa[i]);
        for(int i=0;i<w;i++)
            scanf("%I64d",&bb[i]);
       for(int i=n-1;i>=1;i--)
            a[i]=aa[i]-aa[i-1];//+2*1e9;
       for(int i=w-1;i>=1;i--)
            b[i]=bb[i]-bb[i-1];//+2*1e9;
        printf("%d\n",solve());
    }
    return 0;
}

【CodeForces】471D MUH and Cube Walls KMP或者字符串HASH

标签：io   os   for   数据   sp   问题   c   on   代码   

原文地址：http://blog.csdn.net/u011026968/article/details/39736775