Good Bye 2015 F - New Year and Cleaning

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F - New Year and Cleaning

這題簡直是喪心病狂折磨王。。

思路：容易想到這樣一個轉換，把整個矩形一起移動，矩形移出去的時候相當於一行或者一列。

為了最佳化找到下一個消去的點，我先把原數組擴大兩倍，用了st表加二分去找，然後就MLE， 我又換了

線段樹TLE，最後不把數組擴大兩倍ST表+二分過的。。

 

每次消去的點都是不變的，所以可以做到線性複雜度。

#include<bits/stdc++.h>#define LL long long#define fi first#define se second#define mk make_pair#define PII pair<int, int>#define PLI pair<LL, int>#define ull unsigned long longusing namespace std;const int N = 5e5 + 7;const int inf = 0x3f3f3f3f;const LL INF = 0x3f3f3f3f3f3f3f3f;const int mod = 1e9 + 7;int k, n, m, X[N], Y[N], Log[N];char s[N];struct ST {    int dp[N][20],ty;    void build(int n, int b[], int _ty) {        ty = _ty;        for(int i = 1; i <= n; i++) dp[i][0] = ty * b[i];        for(int j = 1; j <= Log[n]; j++)            for(int i = 1; i+(1<<j)-1 <= n; i++)                dp[i][j] = max(dp[i][j-1], dp[i+(1<<(j-1))][j-1]);    }    int query(int x, int y) {        int k = Log[y - x + 1];        return ty * max(dp[x][k], dp[y-(1<<k)+1][k]);    }} mxx, mnx, mxy, mny;void walk(int &x, int &y, char c) {    if(c == ‘R‘) y++;    else if(c == ‘L‘) y--;    else if(c == ‘U‘) x--;    else x++;}bool check(int l, int r, int x, int y, int lenr, int lenc) {    int mxX = mxx.query(l, r) - X[l-1];    int mnX = mnx.query(l, r) - X[l-1];    int mxY = mxy.query(l, r) - Y[l-1];    int mnY = mny.query(l, r) - Y[l-1];    if(x+mxX+lenr > n || x+mnX < 0 || y+mxY+lenc > m || y+mnY < 0) return true;    return false;}int main() {    for(int i = -(Log[0]=-1); i < N; i++)        Log[i] = Log[i - 1] + ((i & (i - 1)) == 0);    scanf("%d%d%d%s", &k, &n, &m, s + 1);    int x = 0, y = 0, L = 0, R = 0, D = 0, U = 0, p = 0;    for(int i = 1; i <= k; i++) {        walk(x, y, s[i]);        L = min(L, y); R = max(R, y);        U = min(U, x); D = max(D, x);    }    if(!x && !y) {        if(R - L + 1 <= m && D - U + 1 <= n) {            puts("-1");            return 0;        }    }    x = 0, y = 0;    for(int i = 1; i <= k; i++) {        walk(x, y, s[i]);        X[i] = x; Y[i] = y;    }    mxx.build(k, X, 1);    mnx.build(k, X, -1);    mxy.build(k, Y, 1);    mny.build(k, Y, -1);    x = 0, y = 0;    int lenr = n, lenc = m;    LL ans = 0, t = 0;    while(lenr && lenc) {        int l = p + 1, r = min(k, p + k), pos = -1;        while(l <= r) {            int mid = l + r >> 1;            if(check(p + 1, mid, x, y, lenr, lenc)) r = mid - 1, pos = mid;            else l = mid + 1;        }        if(pos != -1) {            x += X[pos] - X[p];            y += Y[pos] - Y[p];            t = (t + pos - p) % mod;            p = pos;            if(s[p] == ‘U‘) {                lenr--; ans = (ans + 1ll*t*lenc) % mod;                x = 0;            } else if(s[p] == ‘D‘) {                lenr--; ans = (ans + 1ll*t*lenc) % mod;            } else if(s[p] == ‘L‘) {                lenc--; ans = (ans + 1ll*t*lenr) % mod;                y = 0;            } else {                lenc--; ans = (ans + 1ll*t*lenr) % mod;            }            if(p == k) p = 0;        } else {            x += X[k] - X[p];            y += Y[k] - Y[p];            t = (t + k - p) % mod;            p = 0;        }    }    printf("%lld\n", ans);    return 0;}/**/

 

Good Bye 2015 F - New Year and Cleaning