Submission #5675183

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Source Code Expand

#include<bits/stdc++.h>
#define ll long long int
using namespace std;

const int MAXN = 205000;

struct node {
    int next[26];
    int len;
    int sufflink;
    int num;
};

ll len;
string s;
node tree[MAXN]; 
int num;            // node 1 - root with len -1, node 2 - root with len 0
int suff;           // max suffix palindrome
long long ans;

bool addLetter(int pos) {
    int cur = suff, curlen = 0;
    int let = s[pos] - 'a';

    while (true) {
        curlen = tree[cur].len;
        if (pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos])     
            break;  
        cur = tree[cur].sufflink;
    }       
    if (tree[cur].next[let]) {  
        suff = tree[cur].next[let];
        return false;
    }

    num++;
    suff = num;
    tree[num].len = tree[cur].len + 2;
    tree[cur].next[let] = num;

    if (tree[num].len == 1) {
        tree[num].sufflink = 2;
        tree[num].num = 1;
        return true;
    }

    while (true) {
        cur = tree[cur].sufflink;
        curlen = tree[cur].len;
        if (pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos]) {
            tree[num].sufflink = tree[cur].next[let];
            break;
        }       
    }           

    tree[num].num = 1 + tree[tree[num].sufflink].num;

    return true;
}

void initTree() {
    num = 2; suff = 2;
    tree[1].len = -1; tree[1].sufflink = 1;
    tree[2].len = 0; tree[2].sufflink = 1;
}

int main() {
    //assert(freopen("input.txt", "r", stdin));
    //assert(freopen("output.txt", "w", stdout));

    cin>>s;
    len = s.length();

    initTree();

    for (int i = 0; i < len; i++) {
        addLetter(i);
        ans += tree[suff].num;
    }
    ans = ((len)*(len+1))/2LL - ans;
    cout << ans  + 1<< endl;

    return 0;
}

Submission Info

Judge Result