UVA11992 Fast Matrix Operations 快速矩阵操作（线段树）

旧城等待， 2021-12-11 09:25 131阅读 0赞

## 题意：对矩阵有三种操作，第一是让矩阵的每个元素加上某个数，第二是让矩阵得每个元素变成某个数，第三是输出某个子矩阵的数字总和，最大值和最小值。开始时，矩阵得每个元素为0. ##

## 分析：每行建一颗线段树，多维护几个信息。详见《训练指南》P207-208。 ##

## 代码： ##

#include<bits/stdc++.h>
    using namespace std;
    
    const int maxnode = 1<<17;
    
    int _sum, _min, _max, op, x1, x2, y1, y2, x, v;
    
    struct IntervalTree {
      int sumv[maxnode], minv[maxnode], maxv[maxnode], setv[maxnode], addv[maxnode];
    
      // 维护信息
      void maintain(int o, int L, int R) {
        int lc = o*2, rc = o*2+1;
        if(R > L) {
          sumv[o] = sumv[lc] + sumv[rc];
          minv[o] = min(minv[lc], minv[rc]);
          maxv[o] = max(maxv[lc], maxv[rc]);
        }
        if(setv[o] >= 0) { minv[o] = maxv[o] = setv[o]; sumv[o] = setv[o] * (R-L+1); }
        if(addv[o]) { minv[o] += addv[o]; maxv[o] += addv[o]; sumv[o] += addv[o] * (R-L+1); }
      }
    
      // 标记传递
      void pushdown(int o) {
        int lc = o*2, rc = o*2+1;
        if(setv[o] >= 0) {
          setv[lc] = setv[rc] = setv[o];
          addv[lc] = addv[rc] = 0;
          setv[o] = -1; // 清除本结点标记
        }
        if(addv[o]) {
          addv[lc] += addv[o];
          addv[rc] += addv[o];
          addv[o] = 0; // 清除本结点标记
        }
      }
    
      void update(int o, int L, int R) {
        int lc = o*2, rc = o*2+1;
        if(y1 <= L && y2 >= R) { // 标记修改
          if(op == 1) addv[o] += v;
          else { setv[o] = v; addv[o] = 0; }
        } else {
          pushdown(o);
          int M = L + (R-L)/2;
          if(y1 <= M) update(lc, L, M); else maintain(lc, L, M);
          if(y2 > M) update(rc, M+1, R); else maintain(rc, M+1, R);
        }
        maintain(o, L, R);
      }
    
      void query(int o, int L, int R, int add) {
        if(setv[o] >= 0) {
          int v = setv[o] + add + addv[o];
          _sum += v * (min(R,y2)-max(L,y1)+1);
          _min = min(_min, v);
          _max = max(_max, v);
        } else if(y1 <= L && y2 >= R) {
          _sum += sumv[o] + add * (R-L+1);
          _min = min(_min, minv[o] + add);
          _max = max(_max, maxv[o] + add);
        } else {
          int M = L + (R-L)/2;
          if(y1 <= M) query(o*2, L, M, add + addv[o]);
          if(y2 > M) query(o*2+1, M+1, R, add + addv[o]);
        }
      }
    };
    
    const int maxr = 20 + 5;
    const int INF = 1000000000;
    
    IntervalTree tree[maxr];
    
    int main() {
      int r, c, m;
      while(scanf("%d%d%d", &r, &c, &m) == 3) {
        memset(tree, 0, sizeof(tree));
        for(x = 1; x <= r; x++) {
          memset(tree[x].setv, -1, sizeof(tree[x].setv));
          tree[x].setv[1] = 0;
        }
        while(m--) {
          scanf("%d%d%d%d%d", &op, &x1, &y1, &x2, &y2);
          if(op < 3) {
            scanf("%d", &v);
            for(x = x1; x <= x2; x++) tree[x].update(1, 1, c);
          } else {
            _sum = 0; _min = INF; _max = -INF;
            for(x = x1; x <= x2; x++) tree[x].query(1, 1, c, 0);
            printf("%d %d %d\n", _sum, _min, _max);
          }
        }
      }
      return 0;
    }