标签：define row div https code bsp log its blog
Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2).
The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2, col2) = (4, 3), which contains sum = 8.
Example:
Given matrix = [ [3, 0, 1, 4, 2], [5, 6, 3, 2, 1], [1, 2, 0, 1, 5], [4, 1, 0, 1, 7], [1, 0, 3, 0, 5] ] sumRegion(2, 1, 4, 3) -> 8 sumRegion(1, 1, 2, 2) -> 11 sumRegion(1, 2, 2, 4) -> 12
Note:
Solution: can be simplified to add one column and one row to dp(dp[row+1][column+1] )
1 public class NumMatrix { 2 private int[,] dp {get;set;} 3 public NumMatrix(int[,] matrix) { 4 int r = matrix.GetLength(0); 5 int c = matrix.GetLength(1); 6 if(r>0&&c>0) 7 { 8 dp = new int[r, c]; 9 for(int i=0; i<r;i++) 10 { 11 for(int j=0;j<c; j++) 12 { 13 if(i==0&&j==0) 14 { 15 dp[0,0]=matrix[0,0]; 16 } 17 else if(i==0) 18 { 19 dp[0,j]=dp[0,j-1]+matrix[0,j]; 20 } 21 else if(j==0) 22 { 23 dp[i,0] = dp[i-1,0]+matrix[i,0]; 24 } 25 else 26 { 27 dp[i,j] = dp[i-1,j]+dp[i, j-1]-dp[i-1,j-1]+matrix[i,j]; 28 } 29 } 30 } 31 } 32 33 } 34 35 public int SumRegion(int row1, int col1, int row2, int col2) { 36 if(row1==0 && col1==0) 37 { 38 return dp[row2,col2]; 39 } 40 else if(col1==0) 41 { 42 return dp[row2, col2]-dp[row1-1, col2]; 43 } 44 else if(row1==0) 45 { 46 return dp[row2, col2]-dp[row2, col1-1]; 47 } 48 else 49 { 50 return dp[row2, col2]-dp[row1-1, col2]-dp[row2, col1-1]+dp[row1-1, col1-1]; 51 } 52 } 53 }
LeetCode 304. Range Sum Query 2D - Immutable
标签：define row div https code bsp log its blog
原文地址：http://www.cnblogs.com/MiaBlog/p/6041370.html
