【POJ 3415】Common Substrings 长度不小于k的公共子串的个数

长度不小于k的公共子串的个数，论文里有题解，卡了一上午，因为sum没开long long！！！

没开long long毁一生again～～～

以后应该早看POJ里的Discuss啊QAQ

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
const int N = 200003;

int t1[N], t2[N], c[N];
void st(int *x, int *y, int *sa, int n, int m) {
	int i;
	for(i = 0; i < m; ++i) c[i] = 0;
	for(i = 0; i < n; ++i) ++c[x[y[i]]];
	for(i = 1; i < m; ++i) c[i] += c[i - 1];
	for(i = n - 1; i >= 0; --i) sa[--c[x[y[i]]]] = y[i];
}
void mkhz(int *a, int *sa, int n, int m) {
	int *t, *x = t1, *y = t2, i, j, p;
	for(i = 0; i < n; ++i) x[i] = a[i], y[i] = i;
	st(x, y, sa, n, m);
	for(p = 1, j = 1; p < n; j <<= 1, 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;
		st(x, y, sa, n, m);
		for(t = x, x = y, y = t, p = 1, x[sa[0]] = 0, i = 1; i < n; ++i)
			x[sa[i]] = y[sa[i]] == y[sa[i - 1]] && y[sa[i] + j] == y[sa[i - 1] + j] ? p - 1 : p++;
	}
}
void mkh(int *r, int *sa, int *rank, int *h, int n) {
	int i, j, k = 0;
	for(i = 1; i <= n; ++i) rank[sa[i]] = i;
	for(i = 1; i <= n; h[rank[i++]] = k)
		for(k ? --k : 0, j = sa[rank[i] - 1]; r[i + k] == r[j + k]; ++k);
}

char s[N];
int a[N], sa[N], rank[N], h[N], n, k, sta[N], top, tmp, mark[N];
long long sum[N];
int main() {
	while (scanf("%d", &k), k) {
		scanf("%s", s + 1);
		tmp = strlen(s + 1);
		s[++tmp] = 1;
		scanf("%s", s + tmp + 1);
		n = strlen(s + 1);
		for(int i = 1; i <= n; ++i) a[i] = s[i];
		mkhz(a, sa, n + 1, 130);
		mkh(a, sa, rank, h, n);
		long long ans = 0;
		for(int i = 1; i <= n; ++i) {
			if (h[i] < k) {
				top = sum[0] = sum[1] = 0;
			} else {
				for(int j = top; sta[j] > h[i] - k + 1 && j; --j) {
					sum[mark[j]] += h[i] - k + 1 - sta[j];
					sta[j] = h[i] - k + 1;
				}
				sta[++top] = h[i] - k + 1;
				if (sa[i - 1] < tmp) mark[top] = 0;
				if (sa[i - 1] > tmp) mark[top] = 1;
				sum[mark[top]] += h[i] - k + 1;
				if (sa[i] < tmp) ans += sum[1];
				if (sa[i] > tmp) ans += sum[0];
			}
		}
		printf("%lld
", ans);
	}
	return 0;
}

没开long long，毁我青春，耗我钱财，颓我精神==