zoj 2859 Matrix Searching

人生第一棵二维线段树，哇卡卡卡卡卡卡卡卡！！！

虽然是看着资料写成的吧。

写了好久滴说。

首先遇到的第一个难题是，建树问题。T T。开始我传递的是指针，发现怎么建都不对 = =。后来直接都用全局的调用，参数加个父树的线段的下标，虽然有点麻烦，但是确实是个办法。

还有就是，对C++知识不了解 = = ，导致形参赋值给形参= = 。。

第二个难题是更新啊。

这个题是要求子矩阵中的最小元素，更新的时候，当前父树的最小值，跟子树在相同区间的最小值有关系（感觉有点像DP）。

这个还是比较水的，不知道难的会咋样 = =。。。反正这个写过后，我真的不想手写二维线段树了 T T。。

#include <queue>#include <stack>#include <math.h>#include <stdio.h>#include <stdlib.h>#include <iostream>#include <limits.h>#include <string.h>#include <string>#include <algorithm>#define MID(x,y) ( ( x + y ) >> 1 )#define L(x) ( x << 1 )#define R(x) ( x << 1 | 1 )#define BUG puts("here!!!")using namespace std;const int MAX = 310;struct Tnode{int l,r,min;int getlen() { return r - l;}int getmid() { return MID(l,r);}void lr(int ll,int rr){ l = ll; r = rr;}};struct T2node{ int l,r; Tnode son[MAX<<2];int getlen() { return r - l;}int getmid() { return MID(l,r);}void lr(int ll,int rr){ l = ll; r = rr;}};T2node node[MAX<<2];int a[MAX][MAX];void sub_build(int f,int t,int l,int r){node[f].son[t].lr(l,r);node[f].son[t].min = INT_MAX;if( l == r - 1 ){if( node[f].getlen() == 1 )node[f].son[t].min = a[node[f].l][l];elsenode[f].son[t].min = min(node[L(f)].son[t].min,node[R(f)].son[t].min);return ;}int mid = MID(l,r);sub_build(f,L(t),l,mid);sub_build(f,R(t),mid,r);node[f].son[t].min = min(node[f].son[L(t)].min,node[f].son[R(t)].min);}void Build(int t,int l1,int r1,int l2,int r2){node[t].lr(l1,r1);if( l1 == r1 - 1 ){sub_build(t,1,l2,r2);return ;}int mid = MID(l1,r1);Build(L(t),l1,mid,l2,r2);Build(R(t),mid,r1,l2,r2);sub_build(t,1,l2,r2);}int sub_query(Tnode *node,int t,int l,int r){if( node[t].l >= l && node[t].r <= r )return node[t].min;if( node[t].l == node[t].r - 1 ) return INT_MAX;int mid = node[t].getmid();int ans = INT_MAX;if( l <= mid ) ans = min(ans,sub_query(node,L(t),l,r));if( r > mid ) ans = min(ans,sub_query(node,R(t),l,r));return ans;}int Query(int t,int l1,int r1,int l2,int r2){if( node[t].l >= l1 && node[t].r <= r1 )return sub_query(node[t].son,1,l2,r2);if( node[t].l == node[t].r - 1 ) return INT_MAX;int mid = node[t].getmid();int ans = INT_MAX;if( l1 <= mid ) ans = min(ans,Query(L(t),l1,r1,l2,r2));if( r1 > mid ) ans = min(ans,Query(R(t),l1,r1,l2,r2));return ans;}int main(){int ncases,n,m,x1,y1,x2,y2;scanf("%d",&ncases);while( ncases-- ){scanf("%d",&n);for(int i=0; i<n; i++)for(int k=0; k<n; k++)scanf("%d",&a[i][k]);Build(1,0,n,0,n);scanf("%d",&m);while( m-- ){scanf("%d%d%d%d",&x1,&y1,&x2,&y2);int ans = Query(1,x1-1,x2,y1-1,y2);printf("%d\n",ans);}}return 0;}

改了下，改成建树后集体更新的 = = 。。。慢了好多好多好多。。

#include <queue>#include <stack>#include <math.h>#include <stdio.h>#include <stdlib.h>#include <iostream>#include <limits.h>#include <string.h>#include <string>#include <algorithm>#define MID(x,y) ( ( x + y ) >> 1 )#define L(x) ( x << 1 )#define R(x) ( x << 1 | 1 )#define BUG puts("here!!!")using namespace std;const int MAX = 310;struct Tnode{int l,r,val;int getmid() { return MID(l,r);}int getlen() { return r - l;}void lr(int ll,int rr){ l = ll; r = rr;}};struct T2node{ int l,r; Tnode son[MAX<<2];int getmid() { return MID(l,r);}int getlen() { return r - l;}void lr(int ll,int rr){ l = ll; r = rr;}};T2node node[MAX<<2];int a[MAX][MAX];void sub_build(int f,int t,int l,int r){node[f].son[t].lr(l,r);node[f].son[t].val = INT_MAX;if( l == r - 1 ) return ;int mid = MID(l,r);sub_build(f,L(t),l,mid);sub_build(f,R(t),mid,r);}void Build(int t,int l1,int r1,int l2,int r2){    node[t].lr(l1,r1);sub_build(t,1,l2,r2);if( l1 == r1 - 1 ) return ;int mid = MID(l1,r1);Build(L(t),l1,mid,l2,r2);Build(R(t),mid,r1,l2,r2);}void sub_updata(int f,int t,int l,int r,int val){node[f].son[t].val = min(node[f].son[t].val,val);    if( node[f].son[t].l >= l && node[f].son[t].r <= r ) return ;    if( node[f].son[t].getlen() == 1 ) return ;    int mid = node[f].son[t].getmid();    if( l < mid ) sub_updata(f,L(t),l,r,val);    if( r > mid ) sub_updata(f,R(t),l,r,val);}void Updata(int t,int l1,int r1,int l2,int r2,int val){    sub_updata(t,1,l2,r2,val);    if( node[t].l >= l1 && node[t].r <= r1 ) return ;    if( node[t].getlen() == 1 ) return ;    int mid = node[t].getmid();    if( l1 < mid ) Updata(L(t),l1,r1,l2,r2,val);    if( r1 > mid ) Updata(R(t),l1,r1,l2,r2,val);} int sub_query(Tnode *node,int t,int l,int r){if( node[t].l >= l && node[t].r <= r )return node[t].val;if( node[t].l == node[t].r - 1 ) return INT_MAX;int mid = MID(node[t].l,node[t].r);int ans = INT_MAX;if( l < mid ) ans = min(ans,sub_query(node,L(t),l,r));if( r > mid ) ans = min(ans,sub_query(node,R(t),l,r));return ans;}int Query(int t,int l1,int r1,int l2,int r2){if( node[t].l >= l1 && node[t].r <= r1 )return sub_query(node[t].son,1,l2,r2);if( node[t].l == node[t].r - 1 ) return INT_MAX;int mid = MID(node[t].l,node[t].r);int ans = INT_MAX;if( l1 < mid ) ans = min(ans,Query(L(t),l1,r1,l2,r2));if( r1 > mid ) ans = min(ans,Query(R(t),l1,r1,l2,r2));return ans;}int main(){int ncases,n,m,x1,y1,x2,y2;scanf("%d",&ncases);while( ncases-- ){scanf("%d",&n);Build(1,0,n+1,0,n+1);for(int i=0; i<n; i++)for(int k=0; k<n; k++){scanf("%d",&a[i][k]);Updata(1,i,i+1,k,k+1,a[i][k]);}scanf("%d",&m);while( m-- ){scanf("%d%d%d%d",&x1,&y1,&x2,&y2);int ans = Query(1,x1-1,x2,y1-1,y2);printf("%d\n",ans);}}return 0;}