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  • 【URAL 1297】Palindrome 最长回文子串

    模板题,,,模板打错查了1h+QAQ

    #include<cmath>
    #include<cstdio>
    #include<cstring>
    #include<algorithm>
    using namespace std;
    const int N = 1000003;
    
    int t1[N], t2[N], c[N], f[N][30];
    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(j = 1, p = 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(i = 1; i < n; ++i) printf("%d ", sa[i]); puts("");
    		for(t = x, x = y, y = t, p = 1, x[sa[0]] = 0, p = 1, 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 k = 0, i, j;
    	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);
    }
    void mkst(int *h, int n) {
    	int k = floor(log((double)n) / log(2.0));
    	for(int i = 1; i <= n; ++i)
    		f[i][0] = h[i];
    	for(int j = 1; j <= k; ++j)
    		for(int i = 1; i <= n; ++i) {
    			if (i + (1 << j) - 1 > n) break;
    			f[i][j] = min(f[i][j - 1], f[i + (1 << (j - 1))][j - 1]);
    		}
    }
    
    char s[N];
    int n, sa[N], a[N], rank[N], h[N];
    int rmq(int l, int r) {
    	l = rank[l]; r = rank[r];
    	if (l > r) swap(l, r); ++l;
    	int k = floor(log((double)(r - l + 1)) / log(2.0));
    	return min(f[l][k], f[r - (1 << k) + 1][k]);
    }
    int main() {
    	while (scanf("%s", s + 1) != EOF) {
    		n = strlen(s + 1);
    		for(int i = 1; i <= n; ++i) a[i] = s[i];
    		a[n + 1] = 126;
    		for(int i = 1; i <= n; ++i)
    			a[n + 1 + i] = a[n + 1 - i];
    		mkhz(a, sa, n * 2 + 2, 130);
    		mkh(a, sa, rank, h, n * 2 + 1);
    		mkst(h, n * 2 + 1);
    //		for(int i = 1; i <= n * 2 + 1; ++i) printf("%d ", sa[i]); puts("");
    //		for(int i = 1; i <= n * 2 + 1; ++i) printf("%d ", rank[i]); puts("");
    		int ans = 0, x, h, t;
    		for(int i = 1; i <= n; ++i) {
    //			ans = max(ans, rmq(i, 2 * n + 2 - i) * 2 - 1);
    //			if (i != 1 && a[i - 1] == a[i]) ans = max(ans, rmq(i, 2 * n + 3 - i) * 2);
    			if ((x = rmq(i, 2 * n + 2 - i)) * 2 - 1 > ans)
    				ans = x * 2 - 1, h = i - x + 1, t = i + x - 1;
    			if (i != 1 && a[i - 1] == a[i] && (x = rmq(i, 2 * n + 3 - i)) * 2 > ans)
    				ans = x * 2, h = i - x , t = i + x - 1;
    //			printf("%d
    ", ans);
    		}
    		for(int i = h; i <= t; ++i)
    			putchar(s[i]);
    		puts("");
    //		printf("%d
    ", ans);
    	}
    	return 0;
    }
    

    第一次把调试信息放在代码里,会不会显得我很制杖呢?(水题都调了这么多)

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  • 原文地址:https://www.cnblogs.com/abclzr/p/5416800.html
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