[Ahoi2013]差异

　　后缀数组+单调栈

　　代码

 #include<cstdio>
 #include<algorithm>
 #include<cstring>
 using namespace std;
 const int N = ;

 const int MAXN =  N;      

 struct SuffixArray{
     int wa[MAXN];
     int wb[MAXN];
     int wv[MAXN];
     int ws[MAXN];          

     int sa[MAXN];
     int rank[MAXN];
     int height[MAXN];
     int r[MAXN];
     int n;
     int m;                 

     void input(int *val, int len, int Max){
         for (int i = ;i < len;i++)
             r[i] = val[i];
         r[len] = ;
         n = len;
         m = Max;
         calSa();
         calHeight();
     }

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

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

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

     int Log[MAXN];
     int best[][MAXN];
     void initRMQ() {
         Log[] = -;
         for(int i = ;i <= MAXN;i++){
             Log[i]=(i & (i - ))?Log[i - ] : Log[i - ] +  ;
         }
         for(int i = ; i <= n ; i ++) best[][i] = height[i];
         for(int i = ; i <= Log[n] ; i ++) {
             int limit = n - (<<i) + ;
             for(int j = ; j <= limit ; j ++) {
                 best[i][j] = (best[i-][j] > best[i-][j+(<<i>>)]) ? best[i-][j+(<<i>>)] : best[i-][j];
             }
         }
     }
     int lcp(int a,int b) {
         a = rank[a];    b = rank[b];
         if(a > b){
             int t = a;
             a = b;
             b = t;
         }
         a ++;
         int t = Log[b - a + ];
         return (best[t][a] > best[t][b - (<<t) + ])? best[t][b - (<<t) + ] : best[t][a];
     }
 }SA;
 int a[N],i,len,top,stack[N];
 long long ans,sum;
 char s[N];
 int main()
 {
     scanf("%s",&s);
     len=strlen(s);
     for (i=;i<=len;i++)
     {
         ans=ans+(long long)i*(len-);
         a[i-]=s[i-];
     }
     SA.input(a,len,);
     for (i=;i<=len;i++)
     {
         while (SA.height[i]<SA.height[stack[top]])
         {
             sum=sum-(long long)(stack[top]-stack[top-])*SA.height[stack[top]];
             top--;
         }
         top++;stack[top]=i;
         sum=sum+(long long)(stack[top]-stack[top-])*SA.height[stack[top]];
         ans=ans-*sum;
     }
     printf("%lld\n",ans);
 }
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