--- a/python/dp.py	Sun Feb 19 16:35:57 2023 +0100
+++ b/python/dp.py	Sun Feb 19 19:20:34 2023 +0100
@@ -181,3 +181,16 @@
                 bestcoord = (x, y)
     return bestcoord, bestsum
 
+def target_sum(s, target):
+    sums = np.zeros_like(s)
+    for i in range(len(s)):
+        sums[i] = sums[max(0, i-1)] + s[i]
+
+    maxlen = -1
+    firstix, lastix = None, None
+    for i in range(len(s)):
+        for j in range(i+1, len(s)):
+            if sums[j]-(sums[i-1] if i > 0 else 0) == target and (j-i+1) > maxlen:
+                maxlen = j-i+1
+                firstix, lastix = i, j
+    return (firstix, lastix)