BOJ 11658: 구간 합 구하기 3

작성일

https://www.acmicpc.net/problem/11658

  • 2월동안 187문제 풀기(지난달 누적 87개) (70/187)
  • 2차원 펜윅 트리
  • 잘 구현만 하면 됨.
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#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
class Fenwick2D {
  int X, Y;
  vector<vector<LL>> tree;
public:
  Fenwick2D(int x, int y): X(x+1), Y(y+1) {
    tree.resize(X, vector<LL>(Y));
  }

  void update(int x, int y, int val) {
    for(int i = x; i < X; i += i & -i)
      for(int j = y; j < Y; j += j & -j)
        tree[i][j] += val;
  }

  LL query(int x, int y) {
    LL ans = 0;
    for(int i = x; i > 0; i -= i & -i)
      for(int j = y; j > 0; j -= j & -j)
        ans += tree[i][j];
    return ans;
  }
};

int main() {
  int N, M;
  scanf("%d %d", &N, &M);
  vector<vector<LL>> arr(N+1, vector<LL>(N+1));
  Fenwick2D fwt(N,N);
  for(int i = 1; i <= N; i++)
    for(int j = 1; j <= N; j++) {
      scanf("%lld", &arr[i][j]);
      fwt.update(i,j,arr[i][j]);
    }
  for(int i =0; i < M; i++) {
    int cmd, x, y, v, x1,y1,x2,y2;
    scanf("%d", &cmd);
    if(cmd == 0) {
      scanf("%d %d %d", &x, &y, &v);
      fwt.update(x,y,v-arr[x][y]);
      arr[x][y] = v;
    } else {
      scanf("%d %d %d %d", &x1, &y1, &x2, &y2);
      LL a = fwt.query(x1-1,y1-1);
      LL b = fwt.query(x1-1,y2);
      LL c = fwt.query(x2,y1-1);
      LL d = fwt.query(x2,y2);
      printf("%lld\n", d-b-c+a);
    }
  }
}