标签：
1 10 1 2 3 4 5 6 7 8 9 10 Query 1 3 Add 3 6 Query 2 7 Sub 10 2 Add 6 3 Query 3 10 End
Case 1: 6 33 59
区间问题求和。
题意： 给一段区间， 有更新操作和查询操作。
可以用 树状数组 和 线段树 做。
我的线段树 是用 指针 做的。用时 是 420+ ms。
树状数组 用时 是 180+ ms。
线段树code：
#include <cstdio> #include <algorithm> #include <vector> #include <iostream> #include <queue> #include <cstring> #include <string> using namespace std; typedef struct node Node; typedef Node *subtree; struct node { int l; int r; int sum; subtree lt; subtree rt; }; subtree build_st( int m[], int l, int r ); int update_st( subtree L, int spot, int data ); void del_st( subtree L ); void solve( int n ); int query_st( subtree L, int que_l, int que_r ); int main(void) { //freopen( "e://test.txt", "rw+", stdin ); int t, n; while( scanf( "%d", &t ) != EOF ){ for( int i=1; i <= t; ++ i ){ printf( "Case %d:\n", i ); scanf( "%d", &n ); solve( n ); } } } void solve( int n ) { int *_m = new int [ n+1 ]; char add[] = "Add"; char sub[] = "Sub"; char end[] = "End"; char str[ 10 ]; subtree L; int spot, data; for( int i=1; i <= n; ++ i ){ scanf( "%d", _m+i ); } L = build_st( _m, 1, n ); while( scanf( "%s", str ) != EOF && strcmp( str, end ) ){ scanf( "%d%d", &spot, &data ); if( !strcmp( str, add ) ){ update_st( L, spot, data ); } else if( !strcmp( str, sub ) ){ update_st( L, spot, - data ); } else{ printf( "%d\n", query_st( L, spot, data ) ); } } // test //for( int i=1; i <= n; ++ i ){ // printf( "%d ", query_st( L, i, i ) ); //}putchar( ‘\n‘ ); del_st( L ); delete _m; } subtree build_st( int m[], int l, int r ) { subtree p_tmp = new Node; memset( p_tmp, 0, sizeof( Node ) ); p_tmp->l = l; p_tmp->r = r; if( l == r ){ p_tmp->sum = m[ l ]; } else{ int mid = (l+r)>>1; p_tmp->lt = build_st( m, l, mid ); p_tmp->rt = build_st( m, mid+1, r ); p_tmp->sum = p_tmp->rt->sum + p_tmp->lt->sum; } return p_tmp; } int update_st( subtree L, int spot, int data ) { if( L->l == L->r && L->l == spot ){ L->sum += data; } else if( spot >= L->l && spot <= L->r ){ int mid = (L->l+L->r)>>1; L->sum = update_st( L->lt, spot, data ) + update_st( L->rt, spot, data ); } return L->sum; } int query_st( subtree L, int que_l, int que_r ) { if( que_r < L->l || que_l > L->r ){ return 0; } if( que_l <= L->l && L->r <= que_r ){ return L->sum; } return ( query_st( L->lt, que_l, que_r ) + query_st( L->rt, que_l, que_r ) ); } void del_st( subtree L ) { if( L ){ del_st( L->lt ); del_st( L->rt ); delete L; } }
树状数组code：
// 用树形数组 做， 代码果然短小精悍 // 用 switch判断会增加用时， o(╯□╰)o #include <cstdio> #include <cstring> using namespace std; #define low_bit( x ) ( x & ( -x ) ) int sum( int _c[], int _spot ); void update( int _c[], int _spot, int _num, int _n ); void solve( int ); int main(void) { //freopen( "d://test.txt", "rw+", stdin ); int n, t; scanf( "%d", &t ); for( int i=1; i <= t; ++ i ) { printf( "Case %d:\n", i ); scanf( "%d", &n ); solve( n ); } return 0; } void solve( int n ) { int *_c = new int [ n+1 ]; int _num, _num2, _ans; char o[] = "Hello_world"; memset( _c, 0, (n+1)*sizeof( int ) ); for( int i=1; i <= n; ++ i ){ scanf( "%d", &_num ); update( _c, i, _num, n ); } while( scanf( "%s", o ) != EOF && o[0] != ‘E‘ ){ scanf( "%d%d", &_num, &_num2 ); if( !strcmp( o, "Add") ){ update( _c, _num, _num2, n ); } else if( !strcmp( o, "Sub" ) ){ update( _c, _num, -_num2, n ); } else{ _ans = sum( _c, _num2 ) - sum( _c, _num - 1 ); printf( "%d\n", _ans ); } } delete [] _c; } void update( int _c[], int spot, int _num, int _n ) { while( spot <= _n ){ _c[spot] += _num; spot += low_bit( spot ); } } int sum( int _c[], int spot ) { int _sum = 0; while( spot > 0 ){ _sum += _c[ spot ]; spot -= low_bit( spot ); } return _sum; }
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原文地址：http://www.cnblogs.com/seana/p/5369682.html
