【POJ】3415 Common Substrings

后缀数组可解。使用单调栈优化。

/* 3415 */
#include <iostream>
#include <sstream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1

const int maxl = 1e5+5;
const int maxn = maxl * 2;
char as[maxl], bs[maxl];
int a[maxn];
int rank[maxn], height[maxn], sa[maxn];
int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
int S[maxn][2];
int K;

bool cmp(int *r, int a, int b, int l) {
    return r[a]==r[b] && r[a+l]==r[b+l];
}

void da(int *r, int *sa, int n, int m) {
    int i, j, *x=wa, *y=wb, *t, p;
    
    for (i=0; i<m; ++i) wc[i] = 0;
    for (i=0; i<n; ++i) wc[x[i]=r[i]]++;
    for (i=1; i<m; ++i) wc[i] += wc[i-1];
    for (i=n-1; i>=0; --i) sa[--wc[x[i]]] = i;
    for (j=1,p=1; p<n; j*=2, m=p) {
        for (p=0,i=n-j; i<n; ++i) y[p++] = i;
        for (i=0; i<n; ++i) if (sa[i] >= j) y[p++] = sa[i] - j;
        for (i=0; i<n; ++i) wv[i] = x[y[i]];
        for (i=0; i<m; ++i) wc[i] = 0;
        for (i=0; i<n; ++i) wc[wv[i]]++;
        for (i=1; i<m; ++i) wc[i] += wc[i-1];
        for (i=n-1; i>=0; --i) sa[--wc[wv[i]]] = y[i];
        for (t=x,x=y,y=t, x[sa[0]]=0, p=1, i=1; i<n; ++i)
            x[sa[i]] = cmp(y, sa[i-1], sa[i], j) ? p-1:p++;
    }
}

void calheight(int *r, int *sa, int n) {
    int i, j, k = 0;
    
    for (i=1; i<=n; ++i) rank[sa[i]] = i;
    for (i=0; i<n; height[rank[i++]]=k)
    for (k?k--:0, j=sa[rank[i]-1]; r[i+k]==r[j+k]; ++k);
}

void printSa(int n) {
    for (int i=1; i<=n; ++i)
        printf("%d ", sa[i]);
    putchar('
');
}

void printHeight(int n) {
    for (int i=1; i<=n; ++i)
        printf("%d ", height[i]);
    putchar('
');
}

void solve() {
    int n = 0, nn;
    
    for (int i=0; ; ++i) {
        if (as[i] == '') {
            nn = i;
            break;
        }
        a[n++] = as[i];
    }
    a[n++] = 1;
    for (int i=0; ; ++i) {
        if (bs[i] == '') {
            break;
        }
        a[n++] = bs[i];
    }
    a[n] = 0;
    
    da(a, sa, n+1, 130);
    calheight(a, sa, n);
    
    int top;
    __int64 tot, ans = 0;
    
    // handle as with bs
    top = 0;
    tot = 0;
    rep(i, 1, n+1) {
        if (height[i] < K) {
            top = 0;
            tot = 0;
        } else {
            int cnt = 0;
            if (sa[i-1] < nn) {
                ++cnt;
                tot += height[i] - K + 1;
            }
            while (top && height[i]<=S[top-1][0]) {
                --top;
                tot -= 1LL * S[top][1] * (S[top][0] - height[i]);
                cnt += S[top][1];
            }
            S[top][0] = height[i];
            S[top][1] = cnt;
            ++top;
            if (sa[i] > nn)
                ans += tot;
        }
    }
    
    
    tot = 0;
    top = 0;
    rep(i, 1, n+1) {
        if (height[i] < K) {
            tot = 0;
            top = 0;
        } else {
            int cnt = 0;
            if (sa[i-1] > nn) {
                ++cnt;
                tot += height[i] - K + 1;
            }
            while (top && height[i]<=S[top-1][0]) {
                --top;
                tot -= 1LL * S[top][1] * (S[top][0] - height[i]);
                cnt += S[top][1];
            }
            S[top][0] = height[i];
            S[top][1] = cnt;
            ++top;
            if (sa[i] < nn)
                ans += tot;
        }
    }
    
    printf("%I64d
", ans);
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    while (scanf("%d", &K)!=EOF && K) {
        scanf("%s%s", as, bs);
        solve();
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}

 数据发生器。

from random import randint, shuffle
import shutil
import string


def GenDataIn():
    with open("data.in", "w") as fout:
        t = 20
        bound = 10**2
        lc = list(string.lowercase)
        for tt in xrange(t):
            k = randint(1, 10)
            fout.write("%d
" % (k))
            length = randint(100, 500)
            line = ""
            for i in xrange(length):
                idx = randint(0, 25)
                line += lc[idx]
            fout.write("%s
" % line)
            length = randint(100, 500)
            line = ""
            for i in xrange(length):
                idx = randint(0, 25)
                line += lc[idx]
            fout.write("%s
" % line)
        fout.write("0
")
        
                
def MovDataIn():
    desFileName = "F:eclipse_prjworkspacehdojdata.in"
    shutil.copyfile("data.in", desFileName)

    
if __name__ == "__main__":
    GenDataIn()
    MovDataIn()