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  • [SPOJ]DISUBSTR:Distinct Substrings&[SPOJ]SUBST1:New Distinct Substrings

    题面

    Vjudge
    Vjudge

    Sol

    求一个串不同子串的个数
    每个子串一定是某个后缀的前缀,也就是求所有后缀不同前缀的个数
    每来一个后缀(suf(i))就会有,(len-sa[i]+1)的新的前缀,又由于有(height)个重复的,那么就是(len-sa[i]+1-height)的贡献
    两个就只有数组大小的区别

    # include <bits/stdc++.h>
    # define IL inline
    # define RG register
    # define Fill(a, b) memset(a, b, sizeof(a))
    using namespace std;
    typedef long long ll;
    const int _(1010);
    
    int n, a[_], sa[_], rk[_], tmp[_], height[_], t[_], mx, T;
    char s[_];
    
    IL bool Cmp(RG int x, RG int y, RG int k){  return tmp[x] == tmp[y] && tmp[x + k] == tmp[y + k];  }
    
    IL void Suffix_Sort(){
    	RG int m = mx;
    	for(RG int i = 0; i <= m; ++i) t[i] = 0;
    	for(RG int i = 1; i <= n; ++i) ++t[rk[i] = a[i]];
    	for(RG int i = 1; i <= m; ++i) t[i] += t[i - 1];
    	for(RG int i = n; i; --i) sa[t[rk[i]]--] = i;
    	for(RG int k = 1; k <= n; k <<= 1){
    		RG int l = 0;
    		for(RG int i = n - k + 1; i <= n; ++i) tmp[++l] = i;
    		for(RG int i = 1; i <= n; ++i) if(sa[i] > k) tmp[++l] = sa[i] - k;
    		for(RG int i = 0; i <= m; ++i) t[i] = 0;
    		for(RG int i = 1; i <= n; ++i) ++t[rk[tmp[i]]];
    		for(RG int i = 1; i <= m; ++i) t[i] += t[i - 1];
    		for(RG int i = n; i; --i) sa[t[rk[tmp[i]]]--] = tmp[i];
    		swap(rk, tmp); rk[sa[1]] = l = 1;
    		for(RG int i = 2; i <= n; ++i) rk[sa[i]] = Cmp(sa[i - 1], sa[i], k) ? l : ++l;
    		if(l >= n) break;
    		m = l;
    	}
    	for(RG int i = 1, h = 0; i <= n; ++i){
    		if(h) --h;
    		while(a[i + h] == a[sa[rk[i] - 1] + h]) ++h;
    		height[rk[i]] = h;
    	}
    }
    
    IL int Calc(){
    	RG int ans = n - sa[1] + 1;
    	for(RG int i = 2; i <= n; ++i) ans += n - sa[i] + 1 - height[i];
    	return ans;
    }
    
    int main(RG int argc, RG char* argv[]){
    	scanf("%d", &T);
    	while(T--){
    		scanf(" %s", s + 1);
    		n = strlen(s + 1); mx = 0;
    		for(RG int i = 1; i <= n; ++i) a[i] = s[i], mx = max(mx, a[i]);
    		Suffix_Sort();
    		printf("%d
    ", Calc());
    	}
        return 0;
    }
    
    
    
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  • 原文地址:https://www.cnblogs.com/cjoieryl/p/8349453.html
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