[Ahoi2013]差异

　　后缀数组+单调栈
　　代码
  1 #include<cstdio>
  2 #include<algorithm>
  3 #include<cstring>
  4 using namespace std;
  5 const int N = 501000;
  6 
  7 const int MAXN =  N;      
  8 
  9 struct SuffixArray{
 10     int wa[MAXN];          
 11     int wb[MAXN];            
 12     int wv[MAXN];           
 13     int ws[MAXN];          
 14 
 15     int sa[MAXN];           
 16     int rank[MAXN];        
 17     int height[MAXN];      
 18     int r[MAXN];            
 19     int n;           
 20     int m;                 
 21 
 22     void input(int *val, int len, int Max){
 23         for (int i = 0;i < len;i++)
 24             r[i] = val[i];
 25         r[len] = 0;                      
 26         n = len;
 27         m = Max;
 28         calSa();
 29         calHeight();
 30     }
 31 
 32     int cmp(int *r, int a, int b, int l){
 33         return (r[a] == r[b] && r[a + l] == r[b + l]);
 34     }
 35 
 36     void calSa(){                 
 37         int i, j, p, *x = wa, *y = wb, *t;
 38         for (i = 0;i < m;i++) ws[i] = 0;
 39         for (i = 0;i < n + 1;i++) ws[x[i] = r[i]]++;
 40         for (i = 1;i < m;i++) ws[i] += ws[i - 1];
 41         for (i = n;i >= 0;i--) sa[--ws[x[i]]] = i;
 42         for (j = 1, p = 1;p < n + 1;j *= 2, m = p){
 43             for (p = 0, i = n - j + 1;i < n + 1;i++) y[p++] = i;
 44             for (i = 0;i < n + 1;i++) if (sa[i] >= j) y[p++] = sa[i] - j;
 45             for (i = 0;i < n + 1;i++) wv[i] = x[y[i]];
 46             for (i = 0;i < m;i++) ws[i] = 0;
 47             for (i = 0;i < n + 1;i++) ws[wv[i]]++;
 48             for (i = 1;i < m;i++) ws[i] += ws[i - 1];
 49             for (i = n;i >= 0;i--) sa[--ws[wv[i]]] = y[i];
 50             for (t = x, x = y, y = t, p = 1, x[sa[0]] = 0, i = 1; i < n + 1;i++)
 51                 x[sa[i]] = cmp(y, sa[i - 1], sa[i], j) ? p - 1 : p++;
 52         }
 53     }
 54 
 55     void calHeight(){              
 56         int i, j, k = 0;
 57         for (i = 1;i <= n;i++) rank[sa[i]] = i;
 58         for (i = 0;i < n;height[rank[i++]] = k)
 59             for (k?k--:0, j = sa[rank[i]- 1];r[i + k] == r[j + k];k++);
 60     }
 61    
 62     int Log[MAXN];
 63     int best[20][MAXN];
 64     void initRMQ() {            
 65         Log[0] = -1;
 66         for(int i = 1;i <= MAXN;i++){
 67             Log[i]=(i & (i - 1))?Log[i - 1] : Log[i - 1] + 1 ;
 68         }
 69         for(int i = 1; i <= n ; i ++) best[0][i] = height[i];
 70         for(int i = 1; i <= Log[n] ; i ++) {
 71             int limit = n - (1<<i) + 1;
 72             for(int j = 1; j <= limit ; j ++) {
 73                 best[i][j] = (best[i-1][j] > best[i-1][j+(1<<i>>1)]) ? best[i-1][j+(1<<i>>1)] : best[i-1][j];
 74             }
 75         }
 76     }
 77     int lcp(int a,int b) {      
 78         a = rank[a];    b = rank[b];
 79         if(a > b){
 80             int t = a;
 81             a = b;
 82             b = t;
 83         }
 84         a ++;
 85         int t = Log[b - a + 1];
 86         return (best[t][a] > best[t][b - (1<<t) + 1])? best[t][b - (1<<t) + 1] : best[t][a];
 87     }
 88 }SA;
 89 int a[N],i,len,top,stack[N];
 90 long long ans,sum;
 91 char s[N];
 92 int main()
 93 {
 94     scanf("%s",&s);
 95     len=strlen(s);
 96     for (i=1;i<=len;i++)
 97     {
 98         ans=ans+(long long)i*(len-1);
 99         a[i-1]=s[i-1];
100     }
101     SA.input(a,len,200);
102     for (i=1;i<=len;i++)
103     {
104         while (SA.height[i]<SA.height[stack[top]])
105         {
106             sum=sum-(long long)(stack[top]-stack[top-1])*SA.height[stack[top]];
107             top--;
108         }
109         top++;stack[top]=i;
110         sum=sum+(long long)(stack[top]-stack[top-1])*SA.height[stack[top]];
111         ans=ans-2*sum;
112     }
113     printf("%lld
",ans);
114 }
115 //3 1 4 2 5 0