历年NOIP水题泛做
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快noip了就乱做一下历年的noip题目咯..
noip2014 飞扬的小鸟
其实这道题并不是很难,但是就有点难搞 听说男神错了一个小时..
就是$f_{i,j}$表示在第$i$个位置高度为$j$的时候最小点击次数
递推的话对于上升的情况只做一次,后面几次在后面再做..
#include <cstdio> #include <cstring> #include <cstdlib> #include <algorithm> using namespace std; const int Maxn = 10010; const int Maxm = 1010; const int inf = 1e9; int f[2][Maxm]; int n, m, K; int l[Maxn], u[Maxn]; bool p[Maxn]; int X[Maxn], Y[Maxn]; int _min ( int x, int y ){ return x < y ? x : y; } int main (){ int i, j, k; scanf ( "%d%d%d", &n, &m, &K ); l[0] = 0; u[0] = m+1; for ( i = 1; i <= n; i ++ ){ scanf ( "%d%d", &X[i], &Y[i] ); l[i] = 0; u[i] = m+1; } for ( i = 1; i <= K; i ++ ){ int x; scanf ( "%d", &x ); p[x] = true; scanf ( "%d%d", &l[x], &u[x] ); } int st = 0; for ( i = 0; i <= m; i ++ ) f[st][i] = 0; int num = 0; for ( i = 1; i <= n; i ++ ){ st = st^1; for ( j = 0; j <= m; j ++ ) f[st][j] = inf; bool bk = false; for ( j = l[i-1]+1; j < u[i-1]; j ++ ){ if ( f[st^1][j] == inf ) continue; bk = true; f[st][_min(j+X[i],m)] = _min ( f[st][_min(j+X[i],m)], f[st^1][j]+1 ); } for ( j = 0; j <= m; j ++ ){ if ( f[st][j] != inf ) f[st][_min(j+X[i],m)] = _min ( f[st][_min(j+X[i],m)], f[st][j]+1 ); } for ( j = l[i-1]+1; j < u[i-1]; j ++ ){ if ( f[st^1][j] == inf ) continue; if ( j-Y[i] > l[i] && j-Y[i] < u[i] ) f[st][j-Y[i]] = _min ( f[st][j-Y[i]], f[st^1][j] ); } if ( bk == false ){ printf ( "0\n%d\n", num-1 ); return 0; } if ( p[i] == true ) num ++; } int ans = inf; for ( i = 1; i <= m; i ++ ) ans = _min ( ans, f[st][i] ); printf ( "1\n%d\n", ans ); return 0; }
noip2013 货车运输
就是裸的最大瓶颈树..
通俗点说就是最大生成树再用st表维护一下路径最小值..
#include <cstdio> #include <cstring> #include <cstdlib> #include <algorithm> using namespace std; const int Maxn = 10010; const int Maxm = 50010; struct node { int y, next, d; }a[Maxn*2]; int first[Maxn], len; void ins ( int x, int y, int d ){ len ++; a[len].y = y; a[len].d = d; a[len].next = first[x]; first[x] = len; } struct lnode { int x, y, d; }list[Maxm]; bool cmp ( lnode x, lnode y ){ return x.d > y.d; } int n, m, q; int fa[Maxn]; bool fw[Maxn]; int ff ( int x ){ if ( fa[x] == x ) return x; return fa[x] = ff (fa[x]); } int minn[Maxn][15], fat[Maxn][15], dep[Maxn]; int _min ( int x, int y ){ return x < y ? x : y; } void dfs ( int x, int f ){ fw[x] = true; for ( int i = 1; i <= 14; i ++ ){ fat[x][i] = fat[fat[x][i-1]][i-1]; minn[x][i] = _min ( minn[x][i-1], minn[fat[x][i-1]][i-1] ); } for ( int k = first[x]; k; k = a[k].next ){ int y = a[k].y; if ( y == f ) continue; fat[y][0] = x; minn[y][0] = a[k].d; dep[y] = dep[x]+1; dfs ( y, x ); } } int lca ( int x, int y ){ int ret = 0x7fffffff; if ( dep[x] < dep[y] ) swap ( x, y ); for ( int i = 14; i >= 0; i -- ){ if ( dep[fat[x][i]] >= dep[y] ){ ret = _min ( ret, minn[x][i] ); x = fat[x][i]; } } if ( x == y ) return ret; for ( int i = 14; i >= 0; i -- ){ if ( fat[x][i] != fat[y][i] ){ ret = _min ( ret, minn[x][i] ); ret = _min ( ret, minn[y][i] ); x = fat[x][i]; y = fat[y][i]; } } return _min ( ret, _min ( minn[x][0], minn[y][0] ) ); } int main (){ int i, j, k; scanf ( "%d%d", &n, &m ); for ( i = 1; i <= m; i ++ ){ scanf ( "%d%d%d", &list[i].x, &list[i].y, &list[i].d ); } sort ( list+1, list+m+1, cmp ); for ( i = 1; i <= n; i ++ ) fa[i] = i; for ( i = 1; i <= m; i ++ ){ int fx = ff (list[i].x), fy = ff (list[i].y); if ( fx != fy ){ fa[fy] = fx; ins ( list[i].x, list[i].y, list[i].d ); ins ( list[i].y, list[i].x, list[i].d ); } } for ( i = 1; i <= n; i ++ ){ if ( fw[i] == false ){ dep[i] = 1; dfs ( i, 0 ); } } scanf ( "%d", &q ); for ( i = 1; i <= q; i ++ ){ int x, y; scanf ( "%d%d", &x, &y ); int fx = ff (x), fy = ff (y); if ( fx != fy ) printf ( "-1\n" ); else printf ( "%d\n", lca ( x, y ) ); } return 0; }
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