HDU 2795 Billboard
作者:互联网
题目链接:https://vjudge.net/problem/HDU-2795
题目大意:
有一块长度为 H 宽度为 W 的广告牌,现在有 n 则广告要依次贴上去,第 i 则广告的长度为 1 宽度为 w[i],广告要尽量贴得高,其次尽量靠左,求每则广告位于第几行,贴不上就输出-1。
分析:
如果广告牌的所有行剩余宽度的最大值大于等于 w[i],那么这个广告肯定能贴在某一行,可以通过二分的方法继续判断以缩小区间,没错,就是最值线段树。代码如下:
1 #pragma GCC optimize("Ofast") 2 #include <bits/stdc++.h> 3 using namespace std; 4 5 #define INIT() std::ios::sync_with_stdio(false);std::cin.tie(0); 6 #define Rep(i,n) for (int i = 0; i < (n); ++i) 7 #define For(i,s,t) for (int i = (s); i <= (t); ++i) 8 #define rFor(i,t,s) for (int i = (t); i >= (s); --i) 9 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i) 10 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i) 11 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i) 12 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i) 13 14 #define pr(x) cout << #x << " = " << x << " " 15 #define prln(x) cout << #x << " = " << x << endl 16 17 #define LOWBIT(x) ((x)&(-x)) 18 19 #define ALL(x) x.begin(),x.end() 20 #define INS(x) inserter(x,x.begin()) 21 22 #define ms0(a) memset(a,0,sizeof(a)) 23 #define msI(a) memset(a,inf,sizeof(a)) 24 #define msM(a) memset(a,-1,sizeof(a)) 25 26 #define MP make_pair 27 #define PB push_back 28 #define ft first 29 #define sd second 30 31 template<typename T1, typename T2> 32 istream &operator>>(istream &in, pair<T1, T2> &p) { 33 in >> p.first >> p.second; 34 return in; 35 } 36 37 template<typename T> 38 istream &operator>>(istream &in, vector<T> &v) { 39 for (auto &x: v) 40 in >> x; 41 return in; 42 } 43 44 template<typename T1, typename T2> 45 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) { 46 out << "[" << p.first << ", " << p.second << "]" << "\n"; 47 return out; 48 } 49 50 typedef long long LL; 51 typedef unsigned long long uLL; 52 typedef pair< double, double > PDD; 53 typedef pair< int, int > PII; 54 typedef set< int > SI; 55 typedef vector< int > VI; 56 typedef map< int, int > MII; 57 typedef vector< LL > VL; 58 typedef vector< VL > VVL; 59 const double EPS = 1e-10; 60 const int inf = 1e9 + 9; 61 const LL mod = 1e9 + 7; 62 const int maxN = 2e5 + 7; 63 const LL ONE = 1; 64 const LL evenBits = 0xaaaaaaaaaaaaaaaa; 65 const LL oddBits = 0x5555555555555555; 66 67 LL H, W, n; 68 LL w[maxN]; 69 70 #define lson l , mid , rt << 1 71 #define rson mid + 1 , r , rt << 1 | 1 72 73 struct SegmentTree{ 74 int st[maxN << 2]; 75 76 inline void pushUp(int rt) { 77 st[rt] = max(st[rt << 1], st[rt << 1 | 1]); 78 } 79 80 inline void pushDown(int rt) { } 81 82 inline void build(int l, int r, int rt) { 83 if(l >= r) { 84 st[rt] = W; 85 return; 86 } 87 int mid = (l + r) >> 1; 88 build(lson); 89 build(rson); 90 pushUp(rt); 91 } 92 93 // 查到某一行能容纳 x 就更新 94 inline LL queryAndUpdate(LL x, int l, int r, int rt) { 95 if(st[rt] < x) return -1; 96 if(l >= r) { 97 st[rt] -= x; 98 return r; 99 } 100 LL ret = 0; 101 int mid = (l + r) >> 1; 102 if(st[rt << 1] >= x) ret = queryAndUpdate(x, lson); // 前面的行优先 103 else if(st[rt << 1 | 1] >= x) ret = queryAndUpdate(x, rson); 104 105 pushUp(rt); 106 return ret; 107 } 108 }; 109 SegmentTree segTr; 110 111 int main(){ 112 INIT(); 113 while(cin >> H >> W >> n) { 114 For(i, 1, n) cin >> w[i]; 115 if(H >= n) H = n; // 行数大于 n 时,只有前 n 行有用 116 segTr.build(1, H, 1); 117 For(i, 1, n) cout << segTr.queryAndUpdate(w[i], 1, H, 1) << endl; 118 } 119 return 0; 120 }View Code
标签:rt,HDU,const,int,LL,typedef,Billboard,define,2795 来源: https://www.cnblogs.com/zaq19970105/p/10797760.html